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)

Storage proteins of the albumin solubility fraction from seeds of Bertholletia excelsa H.B.K. were separated by reversed-phase high-performance liquid chromatography and their primary structures were determined by gas-phase sequencing on intact polypeptides and on the overlapping tryptic and thermolysin peptides. The 2S storage proteins consist of two subunits linked by disulphide bridges. The large subunit (8.5 kDa) is expressed in at least six different isoforms while the small subunit (3.6 kDa) consists of only one form. These proteins are extremely rich in glutamine, glutamic acid, arginine and the sulphur-containing amino acids cysteine and methionine. One of the variants even contains a sequence of six methionine residues in a row. Comparison with known sequences of 2S proteins of other dicotyledonous plants shows limited but distinct sequence homology. In particular, the positions of the cysteine residues relative to each other appear to be completely conserved, suggesting that tertiary structure constraints imposed by disulphide bridges dominate sequence conservation. It has been proposed that the two subunits of a related protein (the Brassica napus storage protein) is cleaved from a precursor polypeptide [Crouch, M. L., Tenbarge, K. M., Simon, A. E. & Ferl, R. (1983) J. Mol. Appl. Genet. 2,273-283]. The amino acid sequence homology of the Brazil nut protein with the former suggests that a similar protein processing event could occur.
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PMID:The amino-acid sequence of the 2S sulphur-rich proteins from seeds of Brazil nut (Bertholletia excelsa H.B.K.). 375 80

We report the identification of the first representative of the alpha-2-macroglobulin family identified in terrestrial invertebrates. An abundant acidic glycoprotein was isolated from the plasma of the soft tick Ornithodoros moubata. Its molecular mass is about 420 kDa in the native state, whereas in SDS/PAGE it migrates as one band of 190 kDa under nonreducing conditions and a band of 92 kDa when reduced. Chemical deglycosylation reveals that it is composed of two different subunits, designated A and B. The N-terminal amino-acid sequence of subunit A is similar to the N-terminus of invertebrate alpha-2-macroglobulin. Sequence analysis of several internal peptides confirms that the tick protein belongs to the alpha-2-macroglobulin family, and the protein is therefore referred to as tick alpha-macroglobulin (TAM). Functional analyses strengthen this assignment. TAM inhibits trypsin and thermolysin cleavage of the high-molecular-weight substrate azocoll in a manner similar to that of bovine alpha-2-macroglobulin. This effect is abolished by pre-treatment of TAM with methylamine. In the presence of TAM, trypsin is protected against active-site inhibition by soybean trypsin inhibitor. We cloned and sequenced a PCR product containing sequences from both subunits and spanning the N-terminus of subunit B and the putative 'bait region' (a segment of alpha-2-macroglobulin which serves as target for various proteases). This indicates that the two subunits are generated from a precursor polypeptide by post-translational processing.
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PMID:Characterization of an alpha-macroglobulin-like glycoprotein isolated from the plasma of the soft tick Ornithodoros moubata. 1063 16