Crude hirudin (12.7 U//~g), a complex mixture of polypeptides obtained from the leech, could be separated by microbore HPLC. A combination of amino acid analysis, N-terminal microsequencing and chemical as well as enzymatic fragmentation made the primary sequence of the new isohirudins la-IIIb' accessible. The biological activity determined in the thrombin inhibition test showed a comparable value for all of these compounds. The results presented address the question as to whether these isohirudins are true mutations from a family of genes or a family of leeches.

A novel polypeptide inhibitor, AI-3688, which acts upon human pancreatic a-amylase, was isolated from fermentation broth of Streptomyces aureojbciens. The purified peptide contains no unusual amino acids. Its M, is 3936. The primary structure of AI-3688 was elucidated by automatic Edman degradation of the native or modified Inhibitor. Two intramolecular cysteines form a disulphide bridge, thus creating a ring structure consisting of 17 amino acids. Strong sequence homology also exists to another microbrai a-amylase inhibitor, tendamistat (HOE 467). This paper discusses the role of a common partial sequence, -Gln-SerTrp-Arg-Tyr-, present in the loop of both inhibitors as the active site of microbiai peptide ct-amylase inhibitors. cc-AmylaseMicrobial peptide Amino ucid sequence Primary structure

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Extracts of cartilage have been reported to inhibit many serine proteinases and metalloenzymes. Such inhibition may be important in protecting cartilage against degradation by chondrocytic proteinases such as collagenase, stromelysin and by leukocytic proteases, such as elastase. We report here isolation and partial characterization of a 17-kD elastase inhibitor from 0.5 M NaCl extracts of both nasal septum cartilage and articular cartilage, which inhibits elastase and represents 0.08% of the weight of nasal cartilage and 0.002% of the weight of articular cartilage. The protein was highly specific for elastase and did not inhibit cartilage metalloproteinases, suggesting that it may be mainly directed toward protecting cartilage against leukocytic proteases. The inhibitor had a blocked amino-terminus, was high in serine and glycine and lacked carbohydrate. The ease with which the inhibitor was extracted from cartilage suggests that it may function in vivo as a highly abundant elastase inhibitor which is secreted into synovial fluid from cartilage. The inhibitor was shown to be synthesized by bovine articular cartilage in explant culture and nearly all of the metabolically labeled material was secreted into the culture media. The inhibitor cross-reacted with polyclonal antibodies to bovine neck ligament alpha-elastin and antibodies to the inhibitor reacted with bovine neck ligament elastin. The properties of this inhibitor are different than those of any other reported cartilage derived inhibitor.