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Distinct heme active-site structure in lactoperoxidase revealed by resonance Raman spectroscopy. Biochemistry 1993 Sep 28;32(38):10125-30

Date

09/28/1993

Pubmed ID

8399138

DOI

10.1021/bi00089a031

Scopus ID

2-s2.0-0027501847   40 Citations

Abstract

Low-frequency resonance Raman spectra of the cyanide and carbon monoxide adducts of lactoperoxidase are obtained with Soret excitation. The nu(Fe-CN) and delta(Fe-C-N) modes are detected at 360 and 453 cm-1, respectively. Upon the isotopic substitution of 13C14N, 12C15N, and 13C15N, the band at 453 cm-1 in the natural abundance adduct shifts to 448, 452, and 445 cm-1, while the 360-cm-1 peak shifts to 358, 357, and 356 cm-1, respectively. The 360-cm-1 band is shifted to 355 cm-1 when the pH is changed from 7.0 to 10.5. On the basis of a previous normal-mode analysis of the cyanoferric adduct of myeloperoxidase, a bent Fe-C-N linkage is suggested for the cyanide adduct of lactoperoxidase. The nu(Fe-CN) (374 cm-1) and delta(Fe-C-N) (480 cm-1) modes are observed for the cyanide adduct of reduced lactoperoxidase. For the carbon monoxide adduct, the nu(Fe-CO) (533 cm-1) and delta(Fe-C-O) (578 cm-1) modes at pH 7.0 are observed to shift to 498 and 570 cm-1 as the pH is raised from 7.0 to 10.0. The strong intensity of delta(Fe-C-O) at both acid and alkaline pHs, along with a suggested bent structure of the Fe-C-N moiety, implies a narrow heme pocket for lactoperoxidase.

Author List

Hu S, Treat RW, Kincaid JR

Authors

James Kincaid PhD Department Chair and Professor, Biophysical Chemistry in the Chemistry department at Marquette University
Robert W. Treat PhD Associate Professor in the Academic Affairs department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Binding Sites
Cattle
Cyanides
Female
Heme
Lactoperoxidase
Milk
Protein Conformation
Spectrum Analysis, Raman