The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Geometry of the dry-state oligomerization of 2′,3′-cyclic phosphates

Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE 1,2-diaminoethane - HPLC high pressure liquid chromatography - RNase bovine pancreatic ribonuclease A, EC 3.1.4.22 - TEAB triethylammonium bicarbonate - tris tris(hydroxymethyl)aminomethane - UMP(S) uridine monophosphorothioate - U > p uridine cyclic 2,3-phosphate - U > p(S) uridine cyclic 2,3-O, O-phosphorothioate - Up(S)dT (P-thio)uridylylthymidine - U2p(R_p-S)5dT (P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage     

Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase

The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate     

Full 1H NMR assignment of a 24-nucleotide RNA hairpin: Application of the 1H 3D-NOE/2QC experiment

The subject RNA models the binding site for the coat protein of the R17 virus, as well as the ribosome recognition sequence for the R17 replicase gene. With an RNA of this size, overlaps among the sugar protons complicate assignments of the ¹H NMR spectrum. The cross peaks that overlap significantly in 2D-NOE spectra can frequently be resolved by introducing a third, in our approach the double-quantum, frequency axis. In particular the planes in a 3D-NOE/2QC spectrum perpendicular to the 2Q axis are extremely useful, showing a highly informative repeating NOE-2Q pattern. In this experiment substantial J-coupling confers special advantages. This always occurs for geminal pairs (H5/H5 for RNA plus H2/H2 for DNA), as well as for H5/H6, for H3/H4 in sugars with substantial populations of the N-pucker, for H1/H2 for S-puckered sugars, and usually for H2/H3. For the 24-mer RNA hairpin the additional information from the 3D-NOE/2QC spectrum allowed assignment of all of the non-exchangeable protons, eliminating the need for stable-isotope labeling.     

Two-dimensional 1H NMR study of two cyclobutane type photodimers of thymidylyl-(3′→5′)-thymidine

2D NMR spectroscopy and J coupling constant analysis are applied to resolve the structure of two photoproducts of thymidylyl-(35)-thymidine. These products are cyclobutane type thymine dimers possessing the cis-syn (the predominant one) and trans-syn geometry. The cis-syn is formed in an ANTI-ANTI conformation about the N-glycosyl linkages and resembles the normal base-stacked configuration. The glycosidic conformation in solution of the 5 terminal fragment differs from the crystal in which the less common SYN conformation is observed. In this isomer only the sugar pucker of the 3 terminal fragment is changed substantially with respect to the dinucleotide. The trans-syn isomer is formed in a SYN-ANTI glycosidic conformation. In this isomer the sugar puckers of both deoxyribose rings are affected and a preference for a pure 2-endo conformation is observed.Abbreviations dTpdT 2-deoxythymidylyl-(35)-2-deoxythymidine - dTp[]dT cyclobutane type photodimers of dTpdT - dTp- and dTp[]- their 5' terminal fragments (fragment A) - -pdT and-[]pdT their 3 terminal fragments (fragment B) - RP-HPLC reversed-phase high-performance liquid chromatography - COSY two-dimensional correlated spectroscopy - 2D NOE two-dimensional nuclear Overhauser spectroscopy     

Chemoenzymatic galactosialylation with integrated cofactor regeneration

As a precursor for the chemical synthesis of sialylated oligosaccharides, the trisaccharide glycoside Neu5Ac (2-8)Gal(1-4)GlcNAc(1-O)-pent-4-ene was synthesized starting from GlcNAc(1-O)-pent-4-ene, UDP-glucose andN-acetylneuraminic acid in a one pot reaction employing galactosyltransferase and (2-6)sialyl-transferase in a complete cofactor regeneration system.Abbreviations Neu5Ac N-acetylneuraminic acid - CMP-Neu5Ac cytidine 5-monophosphosialate - CMP cytidine 5-monophosphate - CDP cytidine 5-diphosphate - CTP cytidine 5-triphosphate - Gal galactose - GlcNAc N-acetylglucosamine - UDP uridine 5-diphosphate - UDP-Glc uridine-5-diphosphoglucose - UDP-Gal uridine-5-diphosphogalactose - PEP phosphoenolpyruvate     

The formation of peptides from the 2′(3′)-glycyl ester of a nucleotide

Summary We have synthesized 2(3)-O-(glycyl)-adenosine-5-(O-methylphos-phate), an analogue of the 3-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine.The aminolysis of 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.Abbreviations MepA adenosine-5-(O-methylphosphate) - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-gly 2,3-O-(bis-glycyl)-adenosine-5-(O-methylphosphate) - DKP diketopiperazine - gly Et glycine ethyl ester - gly-ser N-glycylserine - O-gly-ser O-glycylserine - O-(gly)-gly-ser O-(glycyl)-glycylserine - Boc-gly N-tert-butyloxycarbonylglycine - MepA-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-Boc-gly 2,3-O-(bis-Boc-glycyl)-adenosine-5(O-methylphosphate) - (gly)₂ diglycine - (gly)₃ triglycine     

Degradation of RNA in Escherichia coli. A hypothesis

Summary A hypothesis to explain RNA degradation in Escherichia coli is proposed. In this hypothesis all classes of RNA are potentially degradable unless they are protected. The proposed mechanism for mRNA degradation requires a combination of endonuclease(s) and exonuclease(s) which degrades RNA in the 3 to 5 direction. Ribosomes attached to the newly synthesized 5 end of an mRNA molecule protect it from being attacked endonucleolytically; a delay in attachment of ribosomes to this end exposes it to endonucleolytic cleavage, followed by exonucleolytic digestion from the newly exposed 3 end to the 5 end. This mechanism is consistent with an overall 5 to 3 direction of degradation for mRNA. Exoribonucleases that degrade polyribonucleotides from the 5 end to 3 end are not required. The 3 end of the messenger is protected by its association with DNA. In order to enable the mRNA to remain anchored to the DNA while serving as an efficient template for protein synthesis, a special region near the 3 end of the mRNA is envisaged. This hypothetical region would not be translated.     

Sugar conformation of a stereospecific 2′-R or 2′-S deuterium-labeled DNA decamer studied with proton-proton J coupling constants

The sugar conformation of a DNA decamer was studied with proton-proton ³J coupling constants. Two samples, one comprising stereospecifically labeled 2-R-²H for all residues and the other 2-S-²H, were prepared by the method of Kawashima et al. [J. Org. Chem. (1995) 60, 6980–6986; Nucleosides Nucleotides (1995) 14, 333–336], the deuterium labeling being highly stereospecific 99% for all 2-²H, 98% for 2-²H of A, C, and T, and 93% for 2-²H of G). The ³J values of all H1-H2 and H1-H2 pairs, and several H2-H3 and H2-H3 pairs were determined by line fitting of 1D spectra with 0.1–0.2 Hz precision. The observed J coupling constants were explained by the rigid sugar conformation model, and the sugar conformations were found to be between C3-exo and C2-endo with _m values of 26° to 44°, except for the second and 3 terminal residues C2 and C10. For the C2 and C10 residues, the lower fraction of S-type conformation was estimated from J_H1H2 and J_H1H2 values. For C10, the N–S two-site jump model or Gaussian distribution of the torsion angle model could explain the observed J values, and 68% S-type conformation or C1-exo conformation with 27° distribution was obtained, respectively. The differences between these two motional models are discussed based on a simple simulation of J-coupling constants.     

Effect of adenosine monophosphates on the flowering of Impatients balsamina L., a qualitative short-day plant

Summary Adenosine monophosphates (AMPs) cause the induction of floral buds in Impatients balsamina L. under strictly non-inductive photoperiods and hasten it under inductive photoperiods, cyclic AMP being more effective than 3- or 5-AMPs in this regard.Abbreviations cyclic AMP cyclic 3,5-adenosine monophosphate     

Poly(U)-directed peptide-bond formation from the 2′(3′)-glycyl esters of adenosine derivatives

Summary The self-condensation of 2(3)-O-glycyl esters of adenosine, adenosine-5-(O-methylphosphate) and P₁, P₂-diadenosine-5-pyrophosphate in 6.2 mM solutions at pH 8.0 and -5°C in the presence of 12.5 mM poly(U) yields approximately 3 times as much diketopiperazine as reactions without poly(U). As the concentration of 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate is decreased from 6.2 mM to 1.5 mM the yield of diketopiperazine in the presence of poly(U) decreases slightly from 6.6% to 5.2%, whereas, in the absence of poly(U) the yield of diketopiperazine decreases substantially from 2.4% to 0.75%. The enhanced yield of diketopiperazine that is attributed to the template action of poly(U) is temperature dependent and is observed only at temperatures below 10°C (5°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) and below 23°C (15°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate. The absence of a template effect at high temperatures is attributed to the melting of the organized helices. The hydrolysis half-lives at pH 8.0 and -5°C of 2(3)-O-(glycyl)-adenosine, 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate), 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate, and 5-O-(glycyl)-adenosine in the presence of poly(U) are substantially larger than their half-lives in the absence of poly(U). The condensation of 2(3)-O-(glycyl)-adenosine yields 5% of 5-O-(glycyl)-adenosine in the presence of poly(U) compared to 0.7% in the absence of poly(U).Abbreviations DKP diketopiperazine - (gly)₂ glycylglycine - (gly)₃ glycylglycylglycine - AppA-gly 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - Ado-2(3)-gly 2(3)-O-(glycyl)-adenosine - Ado-5-gly 5-O-(glycyl)-adenosine - Boc-gly N-tert-butyloxycarbonylglycine - AppA P₁, P₂-diadenosine-5-pyrophosphate - MepA adenosine-5-(O-methylphosphate) - AppA-Boc-gly 2(3)-O-(Boc-glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - Ado-5-Boc-gly 5-O-(Boc-glycyl)-adenosine - Ado-2(3)-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine     

Integration of biochemical functions of different cells of RAT gastric mucosa for hydrochloric acid secretion

Summary The regulation patterns of gastric acid secretion in rats were investigated. Pentagastrin and histamine stimulate gastric acid secretion, but the inhibitors of DNA-dependent synthesis of RNA and of proteins prevent only the pentagastrin action. It has been found that pentagastrin induces histidine decarboxylase in gastric mucosa, ensuring local accumulation of histamine. The latter activates adenylate cyclase and results in 3,5-AMP accumulation in gastric tissues. The administration of pentagastrin, histamine or 3,5-AMP enhances the activity of gastric carbonic anhydrase, the enzyme which takes part in HCI formation. The data suggest that these three compounds act sequentially (pentagastrin histamine 3,5-AMP) and the effect of the last one could be mediated through 3,5-AMP dependent protein kinase. The experiments in vitro demonstrated that gastric carbonic anhydrase can be separated into two isoenzymes and the phosphorylation of one of them by the 3,5-AMP dependent protein kinase sharply increases its activity. The findings raise the possibility that histamine and 3,5-AMP, mediating gastrin action, form together with enzymes (histidine decarboxylase, adenylate cyclase, protein kinase, carbonic anhydrase) a cascade of amplifiers.Autoradiographic studies have shown that [³H]-pentagastrin is not bound by oxyntic cells but adheres preferentially to histamine-producing-like endocrine cells and to the chief cells, while³H-histamine adheres preferentially to oxyntic and to chief cells. Electron microscopy indicates that only pentagastrin (but not histamine) initiates in-like endocrine cells ultrastructural changes characteristic for induction. Pentagastrin, histamine and 3,5-AMP administration produces in oxyntic cells ultrastructural changes typical for the secretion processes.These results lead to assumption that pentagastrin (gastrin) induces histidine decarboxylase in-like endocrine cells of gastric glands. Histamine which is secreted enhances adenylate cyclase activity in the neighbouring oxyntic cells where 3,5-AMP dependent protein kinase activates carbonic anhydrase by means of phosphorylation. These different cells form, probably, a multicellular functional unit for gastric acid secretion.An invited article.     

Contribution to the rotifer fauna of subarctic Greenland (Kangerlussuaq and Ammassalik area)

Six water bodies in the region of Kangerlussuaq, West Greenland (67° 30 N, 50° 46 W), and four near Ammassalik, East Greenland (65° 36 N, 37° 38 W) were sampled. Sixty-nine taxa (2 Bdelloidea, 67 Monogononta) are reported, forty-six of which represent new records for Greenland. Proales pejleri n. sp. is described.     

11 S seed storage proteins fromHelianthus species (Compositae): Biochemical,size and charge heterogeneity

The seeds of 19 sunflower species were compared on the basis of their protein contents and the relative proportions of their protein fractions. The globulin content varied from 50% to about 70% and the albumin content from 18% to 35% according to the species. The level of intermediateMr polypeptides showed a great variability (9.6 to 24.3%). Comparative studies onMr polymorphism were carried out by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of non reduced and/or reduced samples using both mono- and bidimensional procedures. Polypeptide constituents of helianthinin were compared including both number and molecular size (cultivatedH. annuus was used as a standard). Studies focused on differences observed between the major two (Mr 38 000), (Mr 32 000) and (Mr 25 500), (21 000) polypeptides families constituting the main A, B, and C subunits. and polypeptides analyses permit to discriminate easilyH. petiolaris from the other species. Charge polymorphism was studied using isoelectric focusing (IEF) and IEF-PAGE in mono and bidimensional procedures in the presence or absence of 2-mercaptoethanol (2-ME). Only a specific ₄ polypeptide enables an easy discrimination betweenH. petiolaris and all the other species. Detailed nomenclature of the , and , polypeptides constituting the different helianthinin globulin subunits is given via the results of pI andMr analyses. Monodimensional IEF patterns of the more basic albumins (pI > 8.0) appear to provide a more valuable approach to identifying specific protein markers.     

Regioselective alkylation of benzylβ-d-lactoside and its derivatives by stannylation

The preparation of benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside, which is a key intermediate for chemical synthesis of oligosaccharide components of glycosphingolipids, was achieved by an improved method. The 3-O-p-methoxybenzyl and 3-O-methyl derivatives were prepared from benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside through stannylation. By using benzyl -d-lactoside as starting material, benzyl 3-O-methyl-, 3-O-benzyl- and 3-O-p-methoxybenzyl--d-lactoside were regioselectively synthesized using the same procedure.     

5′-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats

Summary Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split,P _i from 5-AMP at a rate of 87 nmol/h per g DNA, and from-glycerophosphate at a rate of 25 nmol/h per g DNAK _m for 5 AMP was about 54 M. Adenosine or theophylline inhibited the 5-AMP hydrolysis. Homogenization of the cells increased the activity toward 5-AMP by 23% and that toward-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5-AMP in cortisone-treated rats.     

Rapid plant regeneration of pea using thidiazuron

A simple and rapid pea regeneration procedure was developed. An average of up to 20 shoots formed from hypocotyl explants of cvs. Sugar Ann and Patriot cultured on Murashige and Skoog basal medium supplemented with 0.5 or 1.0 M thidiazuron (N-phenyl-N-1,2,3-thiadiazol-5-ylurea). Hypocotyls of Puget and Sugar Daddy did not respond. Regenerated shoots rooted rapidly when cultured on Murashige and Skoog basal medium containing either 2.0 M -naphthaleneacetic acid or 1.0–2.0 M indole-3-butyric acid. Seeds were harvested from regenerated plants after only 9–11 weeks.Abbreviations BAP 6-benzyladenine - 2,4-d 2,4-dichlorophenoxy acetic acid - GA₃ gibberellic acid - IBA indole-3-butyric acid - MS Murashige and Skoog (1962) medium - NAA -naphthaleneacetic acid - TDZ thidiazuron (N-phenyl-N-1,2,3-thiadiazol-5-ylurea)     

Prebiotic Formation of ADP and ATP from AMP,Calcium Phosphates and Cyanate in Aqueous Solution

Adenosine-5-triphosphate was synthesized by the phosphorylation of adenosine-5-diphosphate in aqueous solution containing cyanate as a condensing reagent and insoluble calcium phosphate produced from phosphate and calcium chloride. In a similar manner, adenosine-5-diphosphate was synthesized from adenosine-5-monophosphate. When the experiment was carried out in the conditions of 4 °C and pH 5.75, the formation of adenosine-5-diphosphate and adenosine-5-triphosphate from adenosine-5-monophosphate was observed in the yields of 19 and 7%, respectively. The other nucleoside-5-triphosphates were also produced from their respective diphosphates.     

Degradation of the diarylpropane lignin model compound 1-(3′,4′-diethoxyphenyl)-1,3-dihydroxy-2-(4′'-methoxyphenyl)-propane and derivatives by the basidiomycete Phanerochaete chrysosporium

The white rot basidiomycete Phanerochaete chrysosporium metabolized 1-(3,4-diethoxyphenyl)-1,3(dihydroxy)-2-(4'-methoxyphenyl)-propane (XII) in low nitrogen stationary cultures, conditions under which the ligninolytic enzyme system is expressed. 3,4-Diethoxybenzyl alcohol (IV), 1,2(dihydroxy)-1-(4-methoxyphenyl)ethane (XX) and anisyl alcohol were isolated as metabolic products indicating an initial , bond cleavage of this dimer. Exogenously added XX was rapidly converted to anisyl alcohol, indicating that XX is an intermediate in the metabolism of XII. Fungal cleavage of the , bond of 1-(3-4-diethoxyphenyl)-1-(hydroxy)-2-(4'-methoxyphenyl)ethane (XI) also occurred, indicating that a hydroxymethyl group is not a prerequisite for this reaction. P. chrysosporium also metabolized 1-(4-ethoxy-3-methoxyphenyl)-2,2(dihydroxy)-2-(4'-methoxyphenyl)propane-1-ol (XIII). The major products of the degradation of this triol included 4-ethoxy-3-methoxybenzyl alcohol (III) and 2-hydroxy-1-(4-methoxyphenyl)-1-oxoethane (XXI). The nature of the products formed indicates that this triol is also cleaved directly at the , bond. The significant difference in the nature of the products formed from the diaryl propane (XII) and the triol (XIII), however, suggests that XIII is not an intermediate in the major pathway for the degradation of XII. Metabolites were identified after comparison with chemically synthesized standards by GLC-mass spectrometry.Abbreviations GLC Gas liquid chromatography - TMSi trimethylsilyl - TLC thin layer chromatography - MS mass spectrometry     

A practical approach to crosslinking

The various aspects of chemical crosslinking are addressed. Crosslinker reactivity, specificity, spacer arm length and solubility characteristics are detailed. Considerations for choosing one of these crosslinkers for a particular application are given as well as reaction conditions and practical tips for use of each category of crosslinkers.Abbreviations ABH azidobenzoyl hydrazide - ANB- NOS N-5-azido-2-nitrobenzoyloxysuccinimide - ASIB 1-(p-azidosalicylamido)-4-(iodoacetamido)butane - ASBA 4-(p-azidosalicylamido)butylamine - APDP N-[4-(p-azidosalicylamido) butyl]-3(2-pyridyldithio)propionamide - APG p-azidophenyl glyoxal monohydrate - BASED bis-[-(4-azidosalicylamido)ethyl] disulfide - BMH bismaleimidohexane - BS³ bis(sulfosuccinimidyl) suberate - BSOCOES bis[2-(succinimidooxycarbonyloxy)ethyl]sulfone - DCC N,N-dicyclohexylcarbodiimide - DFDNB 1,5-difluoro-2,4-dinitrobenzene - DMA dimethyl adipimidate·2HCl - DMP dimethyl pimelimidate·2HCl - DMS dimethyl suberimidate·2HCl - DPDPB 1,4-di-(3,2-pyridyldithio)propionamido butane - DMF dimethylformamide - DMSO dimethylsulfoxide - DSG disuccinimidyl glutarate - DSP dithiobis(succinimidylpropionate) - DSS disuccinimidyl suberate - DST disuccinimidyl tartarate - DTSSP 3,3-dithiobis (sulfosuccinimidylpropionate) - DTBP dimethyl 3,3-dithiobispropionimidate·2HCl - EDC or EDAC 1-ethyl-3-(3-dimethylaminopropyl)carbodimide hydrochloride - EDTA ethylenediaminetetraacetic acid disodium salt, dihydrate - EGS ethylene glycolbis(succinimidylsuccinate) - GMBS N--maleimidobutyryloxysuccinimide ester - HSAB N-hydroxysuccinimidyl-4-azidobenzoate - HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - MBS m-maleimidobenzoyl-N-hydroxysuccinimide ester - MES 4-morpholineethanesulfonic acid - NHS N-hydroxysuccinimide - NHS-ASA N-hydroxysuccinimidyl-4-azidosalicylic acid - PMFS phenylmethylsulfonyl fluoride - PNP-DTP p-nitrophenyl-2-diazo-3,3,3-trifluoropropionate - SAED sulfosuccinimidyl 2-(7-azido-4-methylcoumarin-3-acetamide) ethyl-1,3-dithiopropionate - SADP N-succinimdyl (4-azidophenyl)1,3-dithiopropionate - SAND sulfosuccinimidyl 2-(m-azido-o-nitrobenzamido)-ethyl-1,3-dithiopropionate - SANPAH N-succinimidyl-6(4-azido-2-nitrophenyl-amino)hexanoate - SASD sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3-dithiopropionate - SATA N-succinimidyl-S-acetylthioacetate - SDBP N-hydroxysuccinimidyl-2,3-dibromopropionate - SIAB N-succinimidyl(4-iodoacetyl)aminobenzoate - SMCC succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate - SMPB succinimidyl 4-(p-maleimidophenyl) butyrate - SMPT 4-succinimidyloxycarbonyl--methyl--(2-pyridyldithio)-toluene - sulfo-BSOCOES bis[2-sulfosuccinimidooxycarbonyloxy) ethyl]sulfone - sulfo-DST disulfosuccinimidyl tartarate - sulfo-EGS ethylene glycolbis(sulfosuccinimidylsuccinate) - sulfo-GMBS N--maleimidobutyryloxysulfosuccinimide ester - sulfo-MBS m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester - sulfo-SADP sulfosuccinimidyl(4-azidophenyldithio)propionate - sulfo-SAMCA sulfosuccinimidyl 7-azido-4-methylcoumarin-3-acetate - sulfo-SANPAH sulfosuccinimidyl 6-(4-azido-2-nitrophenylamino)hexanoate - sulfo-SIAB sulfosuccinimidyl(4-iodoacetyl)aminobenzoate - sulfo-SMPB sulfo-succinimidyl 4-(p-maleimidophenyl)butyrate - sulfo-SMCC sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate - SPDP N-succinimidyl 3-(2-pyridyldithio)propionate