Hematin iron valence in catalase and peroxidase compound I: relationship to free radical reaction mechanism.

The material in this paper is centered on the structure of compound I (first reaction intermediate) in the case of catalase and a classical peroxidase (horseradish peroxidase, HRP). The concept of a pi-cation radical is accepted for HRP but is rejected in the case of catalase. A possible mechanism for catalatic action previously proposed assumes FeV for the hematin iron of catalase and hydride ion transfer in the reduction of FeV by the second molecule of H2O2, no free radical being involved.

A study of the catalase monomer produced by lyophilization.

Lyophilization of Dounce and Mourtzikos beef liver catalase (Prep. Biochem. 11 (1981) 501-523) under specified conditions produced conformationally altered but not completely denatured catalase monomer which retained both significant catalatic activity and peroxidatic activity towards ethanol.

Identification of the FTBL protein of Sumner and Dounce as a leucine aminopeptidase.

The crystalline beef liver protein of Sumner and Dounce (A. L. Dounce, P.

Analysis of the peroxidatic mode of action of catalase.

Catalase is an enzyme which can function either in the catabolism of hydrogen peroxide or in the peroxidatic oxidation of small substrates such as ethanol, methanol, or elemental mercury (Hg0). It has been reported that native catalase can peroxidatically oxidize larger organic molecules (e.g.

An hypothesis for explaining the mechanism of translocation in peptide chain synthesis.

A mechanism is proposed for mRNA translocation during peptide chain synthesis, which involves a reciprocal rotation of the two ribosomal components on each other in such a way as to propel the mRNA along a string of ribosomes on an endoplasmic reticulum membrane or to propel a single ribosome along an mRNA molecule in a membrane-free system. Release of tRNA's is assumed to occur from only one of the two ribosomal components at a time, so that there is no danger of loss of the tRNA's during peptide chain synthesis. The mechanism would make the ribosome an active, dynamic structure in addition to being a platform with catalytic activity which holds the components of peptide chain synthesis in juxtaposition.

A proposed mechanism for the catalatic action of catalase.

A detailed mechanism for catalatic action has been proposed which includes the formation of Chance's catalase compound I in the first step and hydride ion transfer in the second step. The first (oxidative) step involves direct reaction of hematin iron with an ionized H2O2 molecule, followed by an oxidation of the iron to Fe IV. The second step is assumed to depend upon the reductive action of a second H2O2 molecule on Chance's compound I through a catalyzed hybride ion transfer, resulting in the regeneration of uncomplexed catalase.

Isolation of three crystalline proteins from beef liver after partial purification by acetone fractionation.

The isolation of three proteins in crystalline form from ground beef liver is described. These proteins are FTBL protein (Arch. Biochem.

High total histone deoxyribonucleic acid ratios for rat liver nuclei.

The ratios of total histone to DNA for rat liver nuclei isolated by four methods as well as for calf liver nuclei isolated by one method were determined by obtaining the ratios of the total areas of the electrophoretic histone peaks for the liver nuclei to the corresponding total area given by a known amount of standard calf thymus histone. Ratios of total histone to DNA of approx. 2 for rat liver nuclei isolated at pH3.