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Affinity properties of phosvitin: Interaction of phosvitin with serine hydroxymethyl transferase

Lakkey, HV and Rao, AGA and Prakash, V and Krishnaswamy, PR and Savithri, HS and Rao, NA and Ramadoss, CS (1999) Affinity properties of phosvitin: Interaction of phosvitin with serine hydroxymethyl transferase. In: Indian Journal Of Biochemistry & Biophysics, 36 (2). pp. 69-76.

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The affinity of phosvitin with serine hydroxymethyl transferase (SHMT), an acidic multi-subunit protein, was evaluated by measurements of enzyme activity, sedimentation velocity, steady-state fluorescence, circular dichroism and kinetic thermal stability. While the presence of phosvitin had no effect on the SHMT activity, the sedimentation coefficient of SHMT increased from 8.7 S to 12.5 S suggesting the formation of a complex at a SHMT:phosvitin molar ratio of 2:1. Based on steady-state fluorescence quenching measurements an association constant of 2.4 +/- 0.2 x 10(5) M-1 at 25 degrees C was obtained for the interaction of phosvitin with SHMT. The temperature dependency of the association constant in the range 15-35 degrees C suggests the involvement of ionic forces in the interaction. The thermal inactivation of SHMT followed first order kinetics. In the presence of phosvitin the rate constant decreased and half time increased. The circular dichroism measurements suggest that phosvitin interaction does not involve pyridoxal phosphate binding domain of the enzyme. Although minor changes in the secondary structure of the enzyme were observed, the environment around aromatic amino acids did not change significantly.

Item Type: Journal Article
Publication: Indian Journal Of Biochemistry & Biophysics
Publisher: Natl Inst Science Communication
Additional Information: Copyright of this article belongs to Natl Inst Science Communication.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 02 Jan 2009 16:49
Last Modified: 02 Jan 2009 16:49
URI: http://eprints.iisc.ac.in/id/eprint/17773

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