The electron acceptors in ubihydroquinone-cytochrome c reductase (Complex III) derived from beef heart mitochondria were investigated by low temperature electron paramagnetic resonance spectroscopy at 120 K and optical reflectance spectroscopy at 100 K. Three resonances were resolved in the region where the low field lines of low spin ferric heme compounds are usually found. These lines were as...

Human serum albumin (HSA) has been allowed to react with varying amounts of iodine under mild conditions. Almost all of the tyrosyl residues of HSA may be converted to iodotyrosyl residues (primarily diiodotyrosyl) without producing significant changes in the conformation of the protein. Difference spectral measurements in urea show the disappearance of “burled” tyrosyl and the appearance of “b...

There are no two main-group elements that exhibit more similar physical and chemical properties than sulfur and selenium. Nonetheless, Nature has deemed both essential for life and has found a way to exploit the subtle unique properties of selenium to include it in biochemistry despite its congener sulfur being 10,000 times more abundant. Selenium is more easily oxidized and it is kinetically m...

Radioactive precursors are not incorporated into deoxyribonucleic acid in viva until 18 hours after partial hepatectomy (1,2). This lag period may represent the time required for the synthesis of some specific protein which enables DNA synthesis to occur (3). It is known that inhibitors of protein synthesis will inhibit the synthesis of bacteriophage DNA if they are added before DNA synthesis b...

The complete ammo acid sequence of 147 residues has been determined for the major monomeric component of the hemoglobin of the bloodworm, Glycera dibranchiata. The residues at 34 sites (23 %) appear to be identical with those in sperm whale myoglobin. Of the 7 “invariant” residues found in vertebrate hemoglobins only three are present in this molecule: the glycine and phenylalanine residues at ...

Allicin (diallylthiosulfinate) is a defence molecule from garlic (Allium sativum L.) with a broad range of biological activities. Allicin is produced upon tissue damage from the non-proteinogenic amino acid alliin (S-allylcysteine sulfoxide) in a reaction that is catalyzed by the enzyme alliinase. Current understanding of the allicin biosynthetic pathway will be presented in this review. Being ...

An aminopeptidase from Escherichia coli has been purified to homogeneity and crystallized. This peptidase is responsible for about 65% of the hydrolytic activity found in crude extracts toward the substrate methionylalanylserine. It resembles the so-called leucine arninop!ptidase of hog kidney in several respects, including size, metal requirements, and peptide specificity. Evidence based on su...

1. Highly purified arginineand lysine-rich histone was maleylated and then hydrolyzed with trypsin. A large amount of precipitate approximating 35% of the histone appeared during the demaleylation procedure. The precipitate was separated into four fractions on a Sephadex G-50 column and one fraction, tryptic peptide II from the maleylated histone, was found to be the COOH-terminal portion of th...

In order to learn whether the kinetics of transient phosphorylation of sodium plus potassium ion transport adenosine triphosphatase was compatible with the hydrolysis of ATP, computer simulation of experimental data was studied. The enzyme mechanism was described in terms of first order and pseudo-first order reactions. The resulting system of linear first order differential equations was solve...

A very rapid procedure for the preparation of phosphoglycerate mutase from chicken breast muscle is presented. Commercially available frozen chicken breasts may be used. The enzyme is obtained in high yields, and the specific activity of the crystalline homogenous preparations is equal to that of the crystalline enzymes from yeast and rabbit muscle. The chicken breast enzyme requires 2,3-diphos...