Insulin ovine

Before we take leave of primary structures for proteins, there is one last, important realization. Proteins serving the same function in different species may have different primary structures. For example, the primary structures of bovine, ovine, and human insulins are not quite the same. They are closely related but not identical. Different species have discovered different protein solutions for the same biological problem. 

Insulin, RMM about 6000, is made up of two chains of amino adds joined by disulfide linkages. The sequence of amino acids in the two chains (termed A for acidic and B for basic) and the arrangement of the three disulfide bridges were worked out by Sanger and associates in the period 1945-1955.1229 The complete synthesis of both ovine and human insulin was achieved in 1963.1230,1231... 

Travers, M.T., Vallance, A.J., Gourlay, H.T., Gill, C.A., Klein, I., Bottema, C.B., Barber, M.C. 2001. Promoter I of the ovine acetyl-CoA carboxylase-alpha gene an E-box motif at -114 in the proximal promoter binds upstream stimulatory factor (USF)-l and USF-2 and acts as an insulin-response sequence in differentiating adipocytes. Biochem. J. 359, 273-284. 

The cyclodextrins have obvious uses in parenteral formulations, including use as components of vehicles for peptides and other biologicals (ovine growth hormone, lL-2 and insulin)... 

Fic. 2. Displacement of si.jabeled IGF-II ( 50 pg, 200 Ci/g) from microsomal membranes isolated from 90-day ovine placenta (top) or term human placenta (bottom). Peptides tested were human IGF-I and IGF-II prepared in the author s laboratory, and porcine insulin. Bfl represents specific binding in the absence of added peptides 25.9% of total tracer for ovine placenta (40 pg protein per tube) and 14.9% of total for human placenta (100 pg protein per tube). Incubations were for 2 hours at 20°C in 0.3 ml final volume of 30 mmol/liter sodium phosphate buffer pH 7.4 containing 0.25% bovine albumin. 

S-ethylcarbamoyl, AT-o-nitrophenylsulphenyl, -trityl, and O-t-butyl groups has recently been elegantly demonstrated by Wittinghofer [114] in the synthesis of the A5.21 portion of ovine insulin. The protected heptapeptide (32) could be smoothly cyclized and the iV-o-nitrophenylsulphenyl group removed without loss of the S-tetrahydropyranyl group. The synthesis of the A13.21 sequence utilized the A-trityl and S-tetrahydropyranyl combination and the stability of the S-tetrahydropyranyl group to 80% acetic acid is illustrated by the formation of (33). The fully protected nonapeptide was prepared by the azide coupling of A 3.1 g with Ai 7.21. 

Removal of the S-ethylcarbamoyl group was accomplished with 4N-ammonia, liquid ammonia-methanol (1 1) or liquid ammonia alone [9]. The group was also cleaved with IN-aqueous sodium hydroxide, sodium methoxide in methanol, or hydrazine in methanol. Wittinghofer [114] has utilized the S-ethylcarbamoyl group in the synthesis of the A. ij segment of ovine insulin, (32). The group was readily removed using... 

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