Selective cleavage at the single tryptophan residue in bovine somatotropin by 2-(2-nitrophenylsulfenyl)-3-methyl-3' -bromoindolemine

Does Pseudomonas Fluorescens produce N-mercapto-4-formylcarbostyril?

The claim that N-mercapto-4-formylcarbostyril was isolated from Pseudomonas fluorescens strain G308 is questioned since N-thiols appear to be unstable compounds at ambient temperature.

Chemical cleavage of bovine beta-lactoglobulin by BNPS-skatole for preparative purposes: comparative study of hydrolytic procedures and peptide characterization

A comparative study of various procedures for tryptophanyl peptide bond cleavage by BNPS-skatole [2-(2-nitrophenyl)-3-methyl-3-bromoindolenine] was carried out on native and on reduced and alkylated bovine beta-lactoglobulin (BLG). The reaction yield and the composition of the derived products were studied in acetic acid, trifluoroacetic acid (TFA), and ethanol/TFA. For BNPS-skatole removal, extraction by water or ethyl ether was compared with dialysis and gel filtration. The three expected peptides (1-19, 20-61, 62-162) and incomplete cleaved fragments (1-61, 20-162) were separated and characterized by electrophoresis, reverse-phase high-performance liquid chromatography, and mass spectrometry. The highest hydrolysis yield (67.4%) occurred with native BLG cleaved in 88% acetic acid at 47 degrees C for 60 min. Subsequent water extraction and gel filtration led to total recovery of the material, but reagent elimination was only quantitative after gel filtration. Cleavage specificity was ensured by mass spectrometry and the amino acid composition of peptides 1-19 and 62-162. The chemical side reactions identified are discussed.

Poly(ADP-ribose) polymerase from Ehrlich ascites-tumour cells. Amino acid composition, N-terminal analysis and chemical cleavage of the purified protein

Poly(ADP-ribose) polymerase was purified from Ehrlich ascites-tumour cells by two novel methods. Analysis for amino acid composition revealed a high percentage of acidic amino acids or their amides, and of basic amino acids. N-Terminal analysis with dansyl chloride revealed no terminal amino acid, indicating a blocked N-terminal amino group. Analysis by gel electrophoresis of protein treated with 3-bromo-3-methyl-2-[(2-nitrophenylthio)-3H-indole, under conditions where selective cleavage of the polypeptide chain at tryptophan residues is obtained, showed six major peptide bands.