Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.27 (thermolysin)
 1,894 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A fully translated actin biosynthetic intermediate containing N-acetylcysteine at the NH2 terminus has been identified in homogenates of differentiated mouse BC3H1 cerebrovascular smooth muscle cells labeled with L-[35S]cysteine. Thermolysin digestion of the highly acidic NH2-terminal tryptic peptide of this intermediate and electrophoretic analysis of the resulting fragments indicated that the intermediate was a precursor of smooth muscle alpha- isoactin , the major isoactin species in vascular smooth muscle. Carboxypeptidase A digestion of the thermolysin cleavage product corresponding to the first eight amino acid residues of the NH2-terminal tryptic peptide demonstrated an acetylcysteine-glutamate residue at the NH2 terminus. These results imply that the gene for smooth muscle alpha- isoactin , like genes coding for skeletal and cardiac alpha- isoactins , contains a cysteine codon immediately following the initiator methionine codon. Both the methionine and cysteine residues must be removed from the NH2 terminus of the intermediate to yield the mature form of smooth muscle alpha- isoactin . The removal of the cysteine residue in vivo is not direct but apparently involves acetylation of the cysteine and subsequent post-translational cleavage of the resulting acetylcysteine. Such an acetylation-dependent pathway has been demonstrated for removal of cysteine from the NH2 terminus of Drosophila actin synthesized in a cell-free translation system ( Rubenstein , P. A., and Martin, D. J. (1983) J. Biol. Chem. 258, 11354-11360). In vivo pulse-chase experiments indicate that the smooth muscle alpha- isoactin intermediate in BC3H1 cells turns over much more slowly than nonmuscle actin intermediates previously identified in mouse L-cells.
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PMID:A vascular smooth muscle alpha-isoactin biosynthetic intermediate in BC3H1 cells. Identification of acetylcysteine at the NH2 terminus. 672 86

The carboxyl-terminal amino acid sequence of Streptomyces subtilisin inhibitor (SSI) was reinvestigated by analysis of the amino acid sequences of the thermolysin peptides from the C-terminal decapeptide, and the sequence -Val110-Ala-Phe-Phe113, which was reported in J. Biochem. 76, 1191-1209 (1974), was revised to -Val110-Phe-Ala-Phe113. Carboxypeptidase A digestion of SSI resulted in loss of the inhibitory activity in parallel with the release of the carboxyl-terminal four amino acid residues. The resulting modified inhibitor, des(Val110-Phe113)-SSI, possessed almost full inhibitory activity against subtilisin BPN' when the inhibitor was incubated with the enzyme in amounts less than one mol of enzyme per mol of the inhibitor. However, no inhibitor activity was observed when the molar ratio of the inhibitor to the enzyme was less than one. This phenomenon suggests that the carboxyl-terminal four amino acid residues might play an important role in the maintenance of the three-dimensional structure of SSI, which resists the action of the proteinase. The addition of more than 30-fold molar excess of SSI-(104-113)-decapeptide (C-terminal decapeptide of SSI) to the modified inhibitor resulted in refolding of the polypeptide chain, rendering it immune from proteolytic digestion.
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PMID:Importance of the carboxyl-terminal four amino acid residues in the inhibitory activity of Streptomyces subtilisin inhibitor (with a revision of its carboxyl-terminal sequence). 699 52