These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: HIV protease substrate conformation: modulation by cyclophilin A.
    Author: McCornack MA, Kakalis LT, Caserta C, Handschumacher RE, Armitage IM.
    Journal: FEBS Lett; 1997 Sep 01; 414(1):84-8. PubMed ID: 9305737.
    Abstract:
    Cyclophilin A (CyPA), a cytosolic peptidyl-prolyl trans-cis isomerase can accelerate the trans-cis isomerization of Xxx-Pro peptide bonds. One- and two-dimensional 1H-NMR spectroscopy were used to determine that the heptapeptide Ser-Gln-Asn-Tyr-Pro-Ile-Val, a model peptide of an HIV-1 protease cleavage site in the gag polyprotein of HIV-1, is a substrate for CyPA. Experiments revealed a slow exchange about the Tyr-Pro peptide bond with 30 +/- 5% in the cis conformation (pH 1-9). While the interconversion rate is too slow to measure by kinetic NMR methods in the absence of CyPA, these methods, saturation transfer and NOE experiments, established that CyPA enhanced the rate of trans-cis interconversion, a process inhibited by cyclosporin A (CsA). With a substrate:CyPA ratio of 40:1, an interconversion rate of 2.5 s(-1) at 25 degrees C was observed.
    [Abstract] [Full Text] [Related] [New Search]