155223 Results for: "slides-and-cover-glasses&amp"

Supplier: MP Biomedicals

Storage: Store at -20 °C. Store Desiccated. Store Under Nitrogen. Protect from light.
5-Bromo-4-chloro-3-indolyl β-D-galactopyranoside, commonly known as X−Gal, is a histochemical substrate for β−galactosidase.
5-Bromo-4-Chloro-3-Indolyl-β-D-Galactopyranoside is used as indigogenic substrate for β-galactosidase, for detection of β-galactosidase-positive clones, and the identification of lac and bacterial colonies or phage plaques. It is the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac+ genotype. X−Gal is cleaved by β−galactosidase to yield an insoluble blue precipitate. X−Gal is particularly useful in molecular biology applications to detect the activity of β−galactosidase which is frequently used as a reporter gene. In cloning, X−Gal is used to detect insertion of foreign DNA into the lacZ region of plasmid DNA using α-complementation which is based on vectors such as the pUC and the M13mp series that carry a fragment of the β-galactosidase gene encoding an α-fragment of β-galactosidase.

Supplier: Aladdin Scientific

Altiratinib (DCC-2701) is a potent single-digit nanomolar inhibitor ofTRK, Met (c-Met), TIE2, and VEGFR2 kinaseswith IC50 vaules of 0.9 nM, 4.6 nM, and 0.8 nM for TRKA, B, and C, respectively. It inhibits Met (c-Met) and Met (c-Met) mutant with IC50 values in the range of 0.3-6 nM.TargetsMET Y1230C (Cell-free assay); TrkA (Cell-free assay); TrkC (Cell-free assay); MET Y1230C (Cell-free assay); MET D1228N (Cell-free assay) 31650,0.37 nM; 0.85 nM; 0.85 nM; 1.2 nM; 1.3 nMIn vitroAltiratinib is >10-fold selective for MET versus FMS and KIT, and >50-fold selective for MET versus ABL1, FYN, HER1 (EGFR), p38α (MAPK14), PDGFRα, PDGFRβ, RET, and SRC. Altiratinib exhibits IC50s of 0.69 nmol/L in K562 cells, 1.2 nmol/L in SK-N-SH cells for inhibition of NGF-stimulated TRKA phosphorylation.

Supplier: Aladdin Scientific

ARQ 531 ARQ 531 is an ATP-competitive tyrosine kinase inhibitor designed to target BTK with an IC50 of 0.85 nM. It also has a distinct kinase selectivity profile with strong inhibitory activity against several key oncogenic drivers from TEC, Trk and Src family kinases. TargetsBTK (Cell-free assay); BRK (Cell-dree); BRK (Cell-free assay); LCK (Cell-free); LCK (Cell-free assay) 29927,0.85 nM; 2.45 nM; 2.45 nM; 3.86 nM; 3.86 nMIn vitroARQ 531 potently inhibited BTK (IC50 = 0.85 nM), the binding potency was accompanied by long residence time (51 min). ARQ 531 selectively inhibits BCR signaling dependent PI3 K/AKT/mTOR, Ras/Raf/Erk and Rap-GTPase-Cofilin pathways in TMD8 cells. It potently inhibits proliferation of hematological malignant cell lines both sensitive and resistant to ibrutinib addicted to BCR signaling.

Supplier: Labconco

Fully-featured, energy-efficient fume hoods provide an environmentally-friendly solution to ducted fume hoods while simplifying installation due to their compact footprint.

Supplier: MP Biomedicals

Storage: Store at Room Temperature (15-30 °C)
Glycine is a non-essential amino acid. It is only amino acid with no asymmetric carbon and thus is not chiral. It is the major inhibitory neurotransmitter. It is involved in the biosynthesis of the porphyrin rings of hemes and chlorophylls.
Glycine is commonly used in buffer solutions, in electrophoresis and preparative chromatography. A study of the folding of monoclonal antibodies in the presence of glycine and their subsequent purification has been published. The use of glycine in the purification of lipopolysaccharides, lipooligosaccharides, and lipid A has been reported. It is an amino acid for use in cell culture media development applications and existing media formulations. Glycine is commonly used as a component in Tris-glycine and Tris-glycine-SDS running buffers for polyacrylamide gel electrophoresis, a component of Towbin's transfer buffer for Western blots, a buffer substance in cryoenzymology, in osmotic pressure maintenance in isoelectric focusing of erythrocytes, salting-in effect in protein chemistry, and as a buffer component in the coupled phosphatase-kinase reaction for end labelling of restriction fragments. The growth requirements of various microorganisms is reported in the Handbook of Microbiology.
Glycine is a non-chiral amino acid that can be synthesized in the body from the amino acid serine by Serine Hydroxymethyltransferase. Inhibitory neurotransmitter in spinal cord, allosteric regulator of NMDA receptors.

Supplier: Aladdin Scientific

Asciminib (ABL001) is a potent and selective allostericABL1inhibitor with dissociation constant (Kd) of 0.5-0.8 nM and selectivity to the myristoyl pocket of ABL1.TargetsAbl1 (Cell-free assay) 0.45 nMin vitroABL001 is a potent, selective BCR-ABL inhibitor that maintains activity across most mutations, including T315I, with a distinct, allosteric mechanism of action.

Supplier: Aladdin Scientific

AMG 337 AMG 337 is an oral, small molecule, ATP-competitive, highly selective inhibitor of the Met (c-Met) receptor with an IC50 of 1 nM. TargetsMET receptor (Cell-free assay); MET(H1094 R) (Cell-free assay); MET(M1250 T) (Cell-free assay); MET(V1092 I) (Cell-free assay) 1 nM; 1 nM ;4.7 nM; 21.5 nMIn vitroAMG 337 potently inhibits the enzymatic activity of WT MET and a subset of MET mutants found in papillary renal cell carcinoma. The inability of AMG 337 to inhibit the Y1230 and D1228 mutants is likely the result of a disruption of the inactive confirmation of the activation loop in the MET kinase domain. AMG 337 also inhibits cell based HGF-induced MET phosphorylation in PC3 cells with IC50 of 5 nM.

Supplier: SPEX CERTIPREP LLC

Biodiesel Standards
Biodiesel Standards Designed for ASTM D6584 & EN14105

Biodiesel is fast becoming an environmentally friendly alternative to petroleum sources. This fuel source is obtained by esterification of oils derived from plants or animals. To meet the demands of this industry, SPEX CertiPrep offers Biodiesel Certified Reference Materials, as well as glyceride and FAME (Fatty Acids Methyl Esters) impurity standards; all designed to save time and money by eliminating the need to prepare in-house standards.

Our standards are manufactured from the highest purity starting materials and the highest grade of solvents available to guarantee superior quality. These standards are manufactured in a specially designed laboratory built to eliminate contamination issues that may arise during the manufacturing process. The standards then go through a rigorous QC process where a senior chemist approves each lot. This guarantees the standards are accurate and stable at the stated concentrations for all of the components. In addition, all standards are supplied with a detailed, comprehensive Certificate of Analysis.

For a custom standard quote, please visit spexcertiprep.com/customorganics.

Supplier: MP Biomedicals

Diethyl Pyrocarbonate (DEPC) is a chemical used to inactivate RNase enzymes and is sensitive to moisture and pH. DEPC is also sensitive to ammonia, which causes decomposition to urethane, a possible carcinogen.
DEPC is effective as a nuclease inhibitor. Modification reagent for His and Tyr residues in proteins. Robust probe for structural disruptions in dsDNA, reacting with fully or partially unstacked bases. Diethyl Pyrocarbonate is used to modify proteins and nucleic acids.
Modification reagent for His and Tyr residues in proteins. Robust probe for structural disruptions in dsDNA, reacting with fully or partially unstacked bases. Diethyl pyrocarbonate has been used in PCR reaction for treating deionized water, which reduces the risk of RNA being degraded by RNases. It is also used for Dot blot hybridization, to dilute total RNA isolated from different micro-organisms.
Inactivates RNase in solution at about 0.1% (v/v), thus protecting RNA against degradation. It inhibits the ryanodine binding to ryanodine/Ca2+ receptor channels in skeletal muscle in a dose and time dependent manner and increases the Ca2+ permeability of SR vesicles.

Supplier: Labconco

Fully-featured, energy-efficient fume hoods provide an environmentally-friendly solution to ducted fume hoods while simplifying installation. Ideal for oversized equipment.

Supplier: Labconco

Fully-featured, energy-efficient fume hoods provide an environmentally-friendly solution to ducted fume hoods while simplifying installation. Ideal for oversized equipment.

Supplier: Heidolph NA, LLC

The Carousel 6 Plus™ Reaction Station simultaneously heats, stirs, and refluxes multiple samples under an inert atmosphere

Supplier: MP Biomedicals

Storage: Room Temperature, desiccate
Protamine sulfate is a purified mixture of simple protein principles obtained from the sperm or testes of suitable species of fish, which has the property of neutralizing heparin. Because of having many basic amino acids (mostly arginine) protamine contains far greater nitrogen than other proteins. Its molecular weight is relatively small. Histone and other basic proteins in the testes of unmatured fishes convert into protamine along with the growth of the fishes. In the testes, protamine takes the form of nucleoprotamine linked with DNA.
Protamine Sulfate is a raw material for study preparations like insulin compounds, and etc. It is used in separation and refining of vaccines. It is a reagent for removing nucleic acids from enzyme solution for the purpose of easy separation and refining. Protamine in the form of solid lipid nanoparticles (SLN) promoted transfection with plasmid DNA more efficiently and with less cytotoxicity than comparable SLNs composed of Esterquat-1.
Protamine sulfate is a small cationic protein that binds and precipitates DNA. Inhibits lipoprotein lipase. Protamine sulfate shown to inhibit the classical pathway of complement. It inhibits turnover of lipoproteins by lipoprotein lipase.

Supplier: Thermo Scientific Chemicals

The PrepEase® Yeast Plasmid Isolation Kit is designed for the isolation of 2μ plasmids from either yeast patches on plates or from yeast grown in small liquid culture

Supplier: MP Biomedicals

Tweens® are a series of nonionic surfactants derived from sorbitan esters. They are soluble or dispersible in water but differ widely in organic and oil solubilities. Used as oil-in-water emulsifiers in pharmaceuticals, cosmetics, cleaning compounds, etc.
Tween® 80 has been widely used in biochemical applications including: solubilizing proteins, isolating nuclei from cells in culture selective protein extraction growing of tubercule bacilli, and emulsifying and dispersing substances in medicinal and food products. It has little or no activity as an anti-bacterial agent. It has been shown to have an adverse effect on the antibacterial effect of methyl paraben and related compounds. Non-ionic detergent used for selective protein extraction and isolation of nuclei from mammalian cell lines.
Soluble/miscible in water to give a clear yellow solution; miscible with alcohol, dioxane, and ethyl acetate; practically insoluble in liquid paraffin and fixed oils (such as mineral oil).
Autoclaving of solutions is not recommended. Sterile filtering is suggested with a 0.22 micron filter. Tween® may need to be warmed to about 40 °C and alternated with portions of hot distilled water while being poured through the filter.
Store at Room Temperature (15-30 °C).

Supplier: Aladdin Scientific

BS-181 HCl is a highly selectiveCDK7 inhibitor withIC50 of 21 nM. It is more than 40-fold selective for CDK7 than CDK1, 2, 4, 5, 6, or 9. TargetsCDK7 (Cell-free assay) 21 nMIn vitroBS-181 is a small molecule inhibitor of CDK7 in a cell-free environment, which displays more potential activity than roscovitine with IC 50 of 510 nM. Among the CDKs and other 69 kinases from many different classes, BS-181 shows high inhibitory selectivity for CDK7, inhibits CDK2 at concentrations lower than 1 μM which being inhibited 35-fold less potently (IC50 with 880 nM) than CDK7, shows slight inhibition for CDK1, CDK4, CDK5, CDK6 and CDK9 with IC50 values higher than 3.0 μM, and only shows inhibition for several kinases from other classes at high concentrations (>10 μM). BS-181 promotes cell cycle arrest and inhibits the cancer cell growth of a range of tumor types, including breast, lung, prostate and colorectal cancer with IC50 in the range of 11.5 to 37 μM.

Supplier: Aladdin Scientific

APD668 APD668 (JNJ28630368) is a potent GPR119 agonist with EC50s of 2.7 and 33 nM for human and rat forms, respectively.Targetshuman GPR119; rat GPR119 2.7 nM(EC50); 33 nM(EC50)In vitroAPD668 is shown to increase adenylate cyclase activation in HEK293 cells transfected with human GPR119 (but not in non-transfected cells) in a concentration-dependent manner with an EC50 of 23 nM. APD668 also enhanced insulin release from both rat and human isolated pancreatic islets in a glucose-dependent manner. In a standard panel of around 80 known receptors and ion channels, APD668 did not show any binding in excess of 50% of control to any other proteins at concentrations up to 10 μM.In vivoChronic treatment with APD668 showed that blood glucose and glycated hemoglobin (HbA1c) levels could be significantly reduced in Zucker Diabetic Fatty (ZDF) rats over several weeks of dosing.

Supplier: Adipogen

Activation of cells by LPS is mediated by the Toll-like receptor 4 (TLR4). For optimal interaction with LPS, TLR4 requires association with myeloid differentiation protein 2 (MD-2). According to current consensus activation of TLR4 is preceded by the transfer of LPS to membrane-bound (m) or soluble (s) CD14 by LPS-binding protein (LBP). Re-form LPS and lipid A, but not S-form LPS, are capable of inducing TNF-alpha responses also in the absence of CD14. LPS, synthesized by most wild-type (WT) Gram-negative bacteria (S-form LPS), consists of three regions, the O-polysaccharide chain, which is made up of repeating oligosaccharide units, the core oligosaccharide and the lipid A, which harbors the endotoxic activity of the entire molecule. R-form LPS synthesized by the so-called rough (R) mutants of Gram-negative bacteria lacks the O-specific chain. Furthermore, the core-oligosaccharide may be present in different degrees of completion, depending on the class (Ra to Re) to which the mutant belongs. LPS are amphipathic molecules whose hydrophobicity decreases with increasing length of the sugar part. Based upon these differences, S- and R-form LPS show marked differences in the kinetics of their blood clearance and cellular uptake as well as in the ability to induce oxidative burst in human granulocytes and to activate the host complement system.

Supplier: Honeywell Research Chemicals

1,10-Phenanthroline hydrochloride monohydrate, Purity: 99.5-102%, Grade: Analytical, Cas number: 18851-33-7, Molecular Formula: C12H8N2A. HClA. H2O, Molar mass: 234.68 g/mol, Synonyms: o-Phenanthroline hydrochloride monohydrate, Size: 5G

Supplier: MP Biomedicals

Acetyl-CoA is produced via beta-oxidation of fatty acids, via the metabolism of carbohydrates - glucose 6-phosphate to pyruvate to acetyl-CoA and via the catabolism of amino acids. Acetyl-CoA has a number of metabolic opportunities. It is metabolized in the tricarboxylic acid cycle to produce carbon dioxide, water and energy.

Supplier: IMPLEN U.S.A. INC

Implen has become the leading expert for innovative, high-quality spectroscopy instruments and the NanoPhotometer® is trusted by thousands of researchers worldwide.

Supplier: Adipogen

Activation of cells by LPS is mediated by the Toll-like receptor 4 (TLR4), a member of the highly conserved protein family of TLRs, which are specialised in the recognition of microbial components. In mice, defects in TLR4 result in LPS unresponsiveness. For optimal interaction with LPS, TLR4 requires association with myeloid differentiation protein 2 (MD-2). According to current consensus activation of TLR4 is preceded by the transfer of LPS to membrane-bound (m) or soluble (s) CD14 by LPS-binding protein (LBP). This mechanism is believed to be generally true for LPS signaling. Re-form LPS and lipid A, but not S-form LPS, are capable of inducing TNF-alpha responses also in the absence of CD14. LPS, synthesized by most wild-type (WT) Gram-negative bacteria (S-form LPS), consists of three regions, the O-polysaccharide chain, which is made up of repeating oligosaccharide units, the core oligosaccharide and the lipid A, which harbors the endotoxic activity of the entire molecule. R-form LPS synthesized by the so-called rough (R) mutants of Gram-negative bacteria lacks the O-specific chain. Furthermore, the core-oligosaccharide may be present in different degrees of completion, depending on the class (Ra to Re) to which the mutant belongs. Monophosphoryl Lipid A (MPLA) represents a detoxified derivative of Lipid A and constitutes an important adjuvant in prophylactic and therapeutic vaccines.

Supplier: Aladdin Scientific

ASP4132 ASP4132 is a potent and orally active activator of Adenosine Monophosphate-Activated Protein Kinase (AMPK) with EC50 of 0.018 μM. ASP4132 is used as a clinical candidate for the treatment of human cancer. TargetsAMPK (Cell-free assay) 0.018 μM(EC50) In vitro ASP4132 is a new type of AMPK activator with potent AMPK activation activity and attractive selective growth inhibition against human cancer cells, improves aqueous solubility, metabolic stability and animal pharmacokinetics (PK). Studies on ASP4132 have advanced to clinical trials for the treatment of cancer. In vivo The In vivo efficacy of ASP4132 is evaluated via MDA-MB-453 xenografts in nude mice. The tumor growth inhibition (TGI) rate is 29% at 1 mg/kg (p.o.), and the tumor regression rate is 26%, 87% and 96% at 2, 4 and 8 mg/kg, respectively. All doses of ASP4132 are well tolerated over the 21-day dosing window, and no body weight loss is observed.Cell Research(from reference) Cell lines: MDA-MB-453, SK-BR-3, AU565, OCUB-M, Concentrations: 0.3 nM, 1 nM, 3 nM, 10 nM, 30 nM, 100 nM, 300 nM, 1000 nM, 3000 Nm Incubation Time: 2 h, 4 days.

Supplier: Aladdin Scientific

Fluorescent Dye Carboxylic Acids and Their Succinimidyl EstersSuccinimidyl esters are proven to be the best reagents for amine modifications because the amide bonds that are formed are essentially identical to, and as stable as the natural peptide bonds. These reagents are generally stable and show good reactivity and selectivity with aliphatic amines. There are few factors that need be considered when SE compounds are used for conjugation reaction: 1). Solvents:For the most part, reactive dyes are hydrophobic molecules and should be dissolved in anhydrous dimethylformamide (DMF) or dimethylsulfoxide (DMSO). 2). Reaction pH: The labeling reactions of amines with succinimidyl esters are strongly pH dependent. Amine-reactive reagents react with non-protonated aliphatic amine groups, including the terminal amines of proteins and the e-amino groups of lysines. Thus amine acylation reactions are usually carried out above pH 7.5. Protein modifications by succinimidyl esters can typically be done at pH 7.5 to 8.5, whereas isothiocyanates may require a pH 9.0 to 10.0 for optimal conjugations.

Supplier: Genevac

miVac Centrifugal Evaporator Packages can be configured out of the box for maximum convenience.

Supplier: MP Biomedicals

Storage: Store at -20 °C.
Brefeldin A is a fungal metabolite which is a macrocyclic lactone exhibiting a wide range of antibiotic activity. Produced by Penicillium brefeldianum. Blocks binding of the cytosolic coat protein b-COP and ARF to Golgi membranes mediated by protein G. Also blocks protein transportation into post-Golgi compartments. It activates the sphingomyelin cycle. Brefeldin A mediated apoptosis has been observed in human tumor cells.
Brefeldin A reversibly inhibits the intracellular translocation of proteins in eukaryotes, e.g., during transport of proteins to the cell surface for secretion or expression. It has been reported to block the response of cultured cells to cholera toxin. In HepG2 cells, BFA induces two blocks in the secretory pathway; one at the level of the endoplasmic reticulum-Golgi juncture and the other in the trans-Golgi network. Brefeldin A is used in the studies of Brefeldin A-inhibited Guanine Nucleotide-exchange Protein, BIG2, Regulates the Constitutive Release of TNFR1 Exosome-like Vesicles.
Brefeldin A (BFA) is a fungal metabolite which disrupts the structure and function of the Golgi apparatus. BFA is an activator of the sphingomyelin cycle. Brefeldin A-mediated apoptosis has been observed in human tumor cells.

Supplier: MP Biomedicals

Storage: +4 °C
Pyruvic acid is an intermediate in sugar metabolism and in enzymatic carbohydrate degradation (alcoholic fermentation) where it is converted to acetaldehyde and CO2 by carboxylase. In muscle, pyruvic acid (derived from glycogen) is reduced to lactic acid during exertion, which is reoxidized and partially retransformed to glycogen during rest. It improves coliform recovery when present in culture medium. It is involved in a metabolic regulatory pathway activated by mitochondrial oxidants. Pyruvate is involved in respiratory regulation in plants by interacting with alternative oxidase at a conserved cysteine residue. It may help prevent hydrogen peroxide mediated cell death.
Sodium pyruvate is utilized as a component in culture broth and media. Sodium pyruvate is used in Wallen fermentation medium to enhance the conversion of oleic acid to 10-ketostearic acid by Bacillus sphaericus. Sodium pyruvate has also been used to establish stably transfected human B cell lines.
Sodium Pyruvate has shown antioxidant properties and protective effects against oxygen radicals. Pyruvate is produced as part of glycolysis and is an intermediate in many metabolic pathways. It can be converted into acetyl CoA and enter the TCA Cycle.

Supplier: Adipogen

Activation of cells by LPS is mediated by the Toll-like receptor 4 (TLR4). For optimal interaction with LPS, TLR4 requires association with myeloid differentiation protein 2 (MD-2). According to current consensus activation of TLR4 is preceded by the transfer of LPS to membrane-bound (m) or soluble (s) CD14 by LPS-binding protein (LBP). Re-form LPS and lipid A, but not S-form LPS, are capable of inducing TNF-alpha responses also in the absence of CD14. LPS, synthesized by most wild-type (WT) Gram-negative bacteria (S-form LPS), consists of three regions, the O-polysaccharide chain, which is made up of repeating oligosaccharide units, the core oligosaccharide and the lipid A, which harbors the endotoxic activity of the entire molecule. R-form LPS synthesized by the so-called rough (R) mutants of Gram-negative bacteria lacks the O-specific chain. Furthermore, the core-oligosaccharide may be present in different degrees of completion, depending on the class (Ra to Re) to which the mutant belongs. LPS are amphipathic molecules whose hydrophobicity decreases with increasing length of the sugar part. Based upon these differences, S- and R-form LPS show marked differences in the kinetics of their blood clearance and cellular uptake as well as in the ability to induce oxidative burst in human granulocytes and to activate the host complement system.

Supplier: Aladdin Scientific

Calmodulin is a bioactive protein isolated from bovine testes with a molecular weight of 16,7 kDa. The material is derived from cattle born and raised in Sweden, a country where BSE is non-existing. Calmodulin is a calcium-binding protein expressed in many eukaryotic cells. By binding to and regulating various protein targets, it affects cellular processes such as metabolism, nerve growth, apoptosis, inflammation, muscle contraction and memory. Many proteins use Calmodulin as a calcium sensor and signal transducer, as the proteins themselves are not able to bind calcium. The molecule can bind a maximum of four calcium ions and by undergoing post-translational modifications such as acetylation, phosphorylation, proteolytic cleavage and methylation, its functions can potentially be altered. Calmodulin is supplied as a lyophilized white powder or flocculate from 50 mM NH4HCO3 with 10 μM CaCl2. No preservatives are added. The protein content is analyzed by amino acid assay and is never less than 80 % of weighed substance. The material has been subjected to an acid treatment for minimum 30 min. The protein is derived from a single batch and is homogenous. Protein calcium binding studies on the regulation of a multitude of different protein targets; Activation of cyclic nucleotide-dependent phosphodiesterase; Co-factor/activator for kinase studies; Studies of edema factor toxin and anthrax bacteria

Supplier: MP Biomedicals

Chloroform is typically used as a solvent and as a cleansing agent. Procedures have been described for the use of chloroform in lambda plaques storage, lambda cDNA storage, the removal of mineral oil from PCR reaction samples, oligonucleotide purification, a hydroxyl radical footprinting protocol, a transcriptional run-on assay protocol, and an overlay assay for beta-galactosidase activity. It has also been used with phenol in such procedures as DNA recovery from polyacrylamide gels, ethidium bromide removal from DNA preparations, lysis protocols for plasmid DNA isolation, RNase removal, and purification of yeast DNA. A protocol describes the use of chloroform in a high-performance thin-layer chromatography protocol for sphingomyelin analysis. Chloroform can also be used in chloroform/methanol mixtures for the isolation of cardiolipids from Geobacillus stearothermophilus and their subsequent MS analysis. The isolation of the bacteriocin amylovorin L471 from Lactobacillus amylovorus DCE 471 in culture broth has been reported, using chloroform/methanol extraction and precipitation in the procedure. Chloroform/2-butanol mixtures can be used for the extraction of steroid sulfates for analysis by nanoelectrospray ionization mass spectrometry.