Effects of limited tryptic proteolysis of bovine neurophysins on molecular properties of hormone binding, self-association, and antigenicity

Limited tryptic fragmentation of disulfide-intact bovine neurophysins I and II (NP-I and -II, respectively) has been found to cause selective disruption of both hormone binding and neurophysin self-association. Loss of binding interactions, measured as a loss of ability to stimulate retardation of 1...

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Bibliographic Details
Published in:Biochemistry (Easton) 1982-12, Vol.21 (25), p.6458-6465
Main Authors: Abercrombie, David M, Angal, Sarojani, Sequeira, Reginald P, Chaiken, Irwin M
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Cattle
Chromatography, Affinity
Chromatography, High Pressure Liquid
Macromolecular Substances
Neurophysins - immunology
Neurophysins - metabolism
Time Factors
Trypsin - metabolism
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Summary:Limited tryptic fragmentation of disulfide-intact bovine neurophysins I and II (NP-I and -II, respectively) has been found to cause selective disruption of both hormone binding and neurophysin self-association. Loss of binding interactions, measured as a loss of ability to stimulate retardation of 125I-labeled neurophysin on Met-Tyr-Phe-amino-butylaminoagarose, is complete within 3 h at 37 degrees C. Reverse-phase high-performance liquid chromatography (HPLC) analysis of tryptic digests of neurophysin I allows detection of two major protein products and the peptide fragment 1-8. Release of the latter N-terminal piece occurs at about the same rate as loss of binding interactions. Reverse-phase HPLC elution behavior before and after performic acid oxidation and amino acid composition of the protein products led to their identification as NP-I-(9-93) (the 9-93 sequence) and [des-19,20]NP-I-(9-93) (the 9-93 sequence with the dipeptide 19-20 missing) for the more rapidly and more slowly formed species, respectively. NP-I-(9-93), unlike intact neurophysin I, is not retarded strongly by either Met-Tyr-Phe-amino-butylaminoagarose or neurophysin II-Sepharose. In contrast, both NP-I-(9-93) and [des-19,20]NP-I-(9-93) are equally as effective as intact NP-I in binding neurophysin I antibodies. The role of amino-terminal residues in promoting hormone binding, self-association, and antigenic recognition interactions is considered.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00268a022