Ben E. Hallaway

Myocardial creatine phosphate and nucleotides in anoxic cardiac arrest and recovery

In isolated perfused dog hearts, myocardial concentrations of creatine phosphate (CrP) and adenosine triphosphate (ATP) decreased following a 45-min period of anoxia. After partial resuscitation by perfusion of oxygenated blood for 30 min, CrP had risen again to approximately control values but ATP concentration had fallen lower. Increased concentrations of deaminated derivatives of ATP, chiefly inosine, were found in the myocardium and in the perfusion effluent after anoxia. The myocardial inosine was still elevated after resuscitation. We conclude that the dynamic equilibrium involving breakdown and resynthesis of ATP through deamination and reamination is disturbed by periods of anoxia as carried out in these experiments and, in addition, inosine is lost by diffusion into extracellular compartments.

Studies on the effect of reagent and protein charges on reactivity of the β93 sulfhydryl group of human hemoglobin using selected mutations

Abstract The reactivity of the β93 sulfhydryl (SH) group of human oxyhemoglobins with the negatively charged 5,5′-dithiobis(2,2′-nitrobenzoate) and the uncharged 2,2′-dithiodipyridine was determined as a function of pH. Selected mutant hemoglobins having increased oxygen affinity and having residue substitutions altering charge near the SH group (Wood, Malmo, Yakima, Kempsey, Andrew-Minneapolis, Osler, and Chesapeake) were compared to hemoglobin (Hb) A. Although both reagents reacted with GSH at the same rate and with the same enthalpies of activation, the rates with Hb were different and the difference showed a pronounced pH dependence. The charged reagent was sensitive to charges near the SH group; a positive charge increased the rate and a negative one decreased the rate. The uncharged reagent which reacted with Hb A with activation enthalpies similar to those for GSH was insensitive to neighboring charges, but was sensitive to tertiary and quaternary structural changes. The rates obtained with the latter reagent did not correlate with oxygen affinity. The evolutionary aspects of the β93 cysteine in relation to structure and function are reviewed.

Contractile Properties of Glycerol-Extracted Muscle Bundles from the Chronically Failing Canine Heart

Chronic congestive heart failure was induced in dogs by the surgical production of tricuspid insufficiency and pulmonary stenosis. Glycerol-extracted trabecular bundles from the right and left ventricles of these dogs developed significantly less tension than did similar preparations from the hearts of normal dogs. The maximum working capacity of the bundles from failing hearts was lower than that of bundles from normal hearts, hut the rate of hydrolysis of adenosinetriphosphate was the same as that of normal heart preparations. Since glycerol-extracted muscle bundles retain the basic contractile properties of fresh, surviving whole muscle but are free from membrane, neurohormonal, ionic and pH effects and are isolated from energy-supplying systems of muscle, defective contractility and decreased working capacity of muscle bundles from failing hearts may be appropriately ascribed to physiochemical changes in the contractile protein, actomyosin. Such alterations are undoubtedly of structural significance, and are related to the conformation changes in actomyosin which characterize the contractile cycle of muscle.

Extraction and Quantitative Characteristics of Actomyosin in Canine Heart Muscle

The conditions for quantitative extraction of actomyosin from dog heart ventricular muscle were studied. By use of appropriate techniques and conditions, yields of actomyosin comparable to those found by others for a variety of muscles were obtained. The method used could be standardized to give reproducible values with both fresh and frozen muscle. Actomyosin so obtained retained its characteristic properties as evidenced by its viscosity response to ATP and its enzymatic activity.

Changes in conformation and function of hemoglobin and myoglobin induced by adsorption to silica

Abstract Adsorption of myoglobin (Mb) or hemoglobin (Hb) to silica (Cab-O-Sil) causes marked alterations in protein hydrogen exchange kinetics. The exchange is slower for cyanometMb and faster for both cyanometHb and oxyHb in adsorbed state than for the corresponding species in the free state. For Hb, adsorption increases oxygen affinity (P 50 = 12.9 mmHg vs. 16.7 for free) and decreases cooperativity (n = 2.05 vs. 2.87 for free). Myoglobin has the same oxygen affinity in both the free and adsorbed states.

HYDROGEN EXCHANGE IN PROTEINS. EQUILIBRIUM AND KINETIC ISOTOPE EFFECTS IN BOVINE PLASMA ALBUMIN STUDIED WITH TRITIUM AND DEUTERIUM.

Abstract 1. 1. Isotope effects have been investigated by comparing the rates of back exchange of tritium and deuterium from bovine plasma albumin to water at different pH values and at 25°. 2. 2. At times less than 8 h there is more exchange of deuterium than of tritium at both pH 5 and 7.2. This difference is considered to be due to a kinetic isotope effect on exchange rates. 3. 3. After 24 h, when apparent exchange equilibrium has been reached, the extent of exchange is the same with both isotopes indicating the absence of a significant equilibrium isotope effect between deuterium and tritium.

Comparison of the state of deoxyhemoglobin S molecules in solution and in fibers by hydrogen exchange kinetics

Hydrogen exchange kinetics of deoxyhemoglobin S gel and deoxyhemoglobin A solution were compared at 4.8 mM tetramer concentration, 25 degrees C, and in sodium phosphate buffer at pH 7.0 with gamma/2 = 0.2 by means of microdialysis using tritium as a trace label. Cyanomethemoglobin A in solution and as crosslinked crystals were compared under the same conditions. The exchange values from 15 to 10(4) min were fitted to a power law, and the distribution function of exchange rates was calculated. There was no significant difference in the distribution for deoxyhemoglobin S gel and deoxyhemoglobin A. Exchange from crosslinked cyanomethemoglobin crystals was less in the early time region than for the solution state, but after 600 min the exchange curves were the same. This resulted in a larger area for the distribution function, although the predominate rates were nearly the same. The effect of polymerization on conformational fluctuations was very small, smaller than the effect of crosslinking hemoglobin crystals.