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M M Zakin

Publications and source records attributed to M M Zakin.

At least 91 records · Page 5Linked to original sources
PubMed1979

Immunologically active zones in bovine growth hormone.

Antigenic determinant areas were detected in bovine growth hormone fragments 6--124 and 125--149, the former being predominant. Reduction and carboxymethylation of disulfide bridge 53--164 destroys the immunological reactivity of the area which is little affected by reduction and carbamoylmethylation. All the activity found in fragment 6--124 seems to be concentrated in the sequence 87--124.

Animals↗
PubMed1978

Detection of the homology among proteins by immunochemical cross-reactivity between denatured antigens. Application to the threonine and methionine regulated aspartokinases-homoserine dehydrogenases from Escherichia coli K 12.

The two isofunctional enzymes aspartokinases-homoserine dehydrogenases I and II from Escherichia coli K 12 are compared using immunochemical techniques. The antibodies raised against one of these two proteins when in its native state can only recognize the homologous antigen, whether it is native or denatured. Contrarily, the antibodies raised against one of these two proteins when in its denatured state can recognize both the homologous and heterologous denatured antigens. The existence of this cross-reaction only between the two denatured aspartokinases-homoserine dehydrogenases suggests that these two enzymes have some similarity since such a reaction is not detected with several other denatured proteins. The regions involved in this similarity are buried inside the native proteins, and become exposed only upon denaturation. The same results, the existence of a cross-reaction between denatured species and none between the native ones, is obtained with proteolytic fragments derived from these two proteins and endowed with homoserine dehydrogenase activity. This resemblance between the two aspartokinases-homoserine dehydrogenases suggests that these proteins derive from a common ancestor. It is also proposed that such a cross-reaction between two denatured proteins is evidence for an homology between their amino acid sequences, and that the use of denatured proteins as both immunogens and antigens could be useful in detecting sequence homologies.

Alkylation↗
PubMed1977

Immunological properties of two related fragments from human and equine growth hormones.

The immunological properties of a synthetic human growth hormone fragment comprising the amino acids 73 through 128 and of the homologous natural horse growth fragment formed by amino acids 73 through 123, have been comparatively studied. Antisera obtained in rabbits inoculated with the native human hormone or with the fragments, were used. By hemagglutination experiments both fragments have the same reactivity toward the anti-human growth hormone serum, but complement fixation curves detect the existence of at least two populations of antibodies presumably originated against the sequence 73-128 of human growth hormone. Of these, only one of the corresponding antigenic areas is present in the homologous region of equine growth hormone. The known cross-reactivity detected between both hormones is thus partially explained.

Animals↗
PubMed1976

Detection of immunologically active zones in equine growth hormone.

Peptide fragments, obtained from equine growth hormone by cyanogen bromide cleavage and further chemical treatment, were isolated and identified. Their immunological reactivities were tested by hemagglutination and complement fixation methods using rabbit antisera against native hormone. Antigenic determinants were detected in the fragments comprising amino acid sequences 5-72 and 73-123, this last one being predominant. Fragment 124-178 had very low reactivity. Nitration of peptide 73-123 did not modify its immunological properties,but oxidation diminished them. Comparison of the antigenicity of equine growth hormone fragment 73-123 with that of the homologous ovine growth hormone fragment 86-123 lent support to the hypothesis that at least one antigenic determinant area in the horse hormone fragment is dependent on sequence 86-123.

Animals↗