[Frontiers in Bioscience 14, 3286-3291, January 1, 2009]

A peptide YY inhibits the human renin activity in a pH dependent manner

Afroza Sultana1, A.H.M. Nurun Nabi2, Kazal B. Biswas1, Miki Takemoto2, Fumiaki Suzuki1,2

1United Graduate School of Agricultural Science, Gifu University, Yanagido 1-1, Gifu 501-1193 Japan, 2Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu 501-1193 Japan

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Materials and methods
3.1. Isolation of dipeptide YY from proteolytically digested RJ protein fraction
3.2. Preparation of partially purified recombinant sheep angiotensinogen and recombinant human renin
3.3. Preparation of wide range buffer
3.4. Observation of the pH dependence of renin activity
3.5. Renin assay at pH 6.0 .and 8.5 .with and without dipeptide YY
4. Results
4.1. The pH dependence of human renin activity with and without dipeptide YY
4.2. The Kinetic parameters of the inhibition of renin activity with and without dipeptide YY at pH 6.0 .and 8.5
5. Discussion
6. Acknowledgements
7. References

1. ABSTRACT

Royal jelly (RJ) is known to possess several physiological and pharmacological properties. A dipeptide YY derived from RJ proteins is known to inhibit angiotensin converting enzyme (ACE) activity. Our previous study showed that the dipeptide YY inhibited the human renin activity at physiological pH. In this study, we investigated the pH dependency of the inhibitory effect of the dipeptide YY to the renin reaction with angiotensinogen. The renin activity was expressed at a wide pH range with two peaks around at 6.0 and 8.0. The dipeptide YY was found to inhibit the renin activity only at the acidic pH range lower than 8.0. The Ki was estimated 4.6 mM at pH 6.0 when the Km of human renin was determined 0.07 mM using sheep angiotensinogen as the substrate. The Km was 0.25 mM at pH 8.5. A stereo structure of the complex of human renin with the dipeptide YY was modeled to discuss its non inhibitory effect on the renin activity at the basic pH. It possibly owes to a local sift of YY space from the center of renin cleft into the N-domain side of renin molecule at basic pH range higher than 8.0.