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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jbsc/008/01-02/0209-0221

    • Keywords

       

      β-Turn; proline peptides; collagen; prolyl hydroxylase; calcium-binding proteins; protein structure

    • Abstract

       

      We report here two sets of results on proline-containing linear peptides, one of which brings out the role of theβ-turn conformation in the structure of nascent collagen while the other points to the functional importance of the β-turn in calcium-binding proteins. Based on the data on peptides containing the -Pro-Gly-sequence, we had proposed and experimentally verified that theβ-turn conformation in these peptides is a structural requirement for the enzymic hydroxylation of the proline residues in the nascent (unhydroxylated) procollagen molecule. Our recent data, presented here, on the conformation of peptides containing both the -Pro-Gly- and -Gly-Pro-sequences reveal that while theβ-turn in the substrate molecule is required at the catalytic site of prolyl hydroxylase, the polyproline-II structure is necessary for effective binding at the active site of the enzyme. Thus, peptides containing either theβ-turn or the polyproline-II structure alone are found to act only as inhibitors while those with the polyproline-II followed byβ-turn serve as substrates of the enzyme. In another study, we have synthesized the two linear peptides: Boc-Pro-D-Ala-Ala-NHCH3 and Boc-Pro-Gly-Ala-NHCH3 each of which adopts, in solution, a structure with two consecutiveβ-turns, as judged from circular dichroism, infrared and nuclear magnetic resonance data. Drastic spectral changes are seen in these peptides on binding to Ca2+. Both the peptides show a distinct specificity to Ca2+ over Mg2+, Na+ and Li+. A conformational change in the peptides occurs on Ca2+ binding which brings together the carbonyl groups to coordinate with the metal ion. These results imply a functional role for theβ-turn in Ca2+ — binding proteins.

    • Author Affiliations

       

      V S Ananthanarayanan1 S K Attah-poku1 P L Mukkamala1 P H Rehse1

      1. Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland - AIB 3X9, Canada

    • Dates

       
      Published
      August 1985

  • Journal of Biosciences | News

      Forthcoming Special issue.


    • To trigger further research on plant mitochondria, the Journal of Biosciences is bringing out a special issue titled "Plant Mitochondria: Properties and Interactions with Other Organelles".


      Plant mitochondria are quite distinct and have unique features, such as a cyanide-insensitive alternate pathway. They also interact with chloroplasts to optimize photosynthetic carbon assimilation.


      Submissions are welcome until 30 July 2023. The contributions can be original articles, short communications, reviews, or mini-reviews on any topic related to plant mitochondria.


      Authors can submit their articles online at https://www.editorialmanager.com/jbsc/default2.aspx

      Posted on April 12, 2023
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      Posted on July 25, 2019

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