Browsing by Author "Berman, M C"

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    Effects of halogenated hydrocarbons on the respiration of beef heart mitochondria and submitochondrial particles
    (1971) Kewley, Carolyn Florence; Kench, J E; Berman, M C
    The investigations to be presented in this thesis arose from studies on the respiration of mitochondria isolated from pig skeletal muscle. These animals developed the syndrome of Malignant Hypermedia after exposure to halothane - a halogenated hydrocarbon used as an inhalation anesthetic agent.
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    Interaction of nucleotides and cations with the (Ca2+, Mg2+)-ATPase of sarcoplasmic reticulum as determined by fluorescence changes of bound 1-anilino-8-naphthalenesulfonate
    (1983) Arav, R; Aderem, A A; Berman, M C
    The changes in fluorescence of 1-anilino-8-naphthalenesulfonate (ANS-) have been used to determine binding of ligands to the (Ca2+, Mg2+)-ATPase of sarcoplasmic reticulum vesicles, isolated from rabbit skeletal muscle. ANS- binds to sarcoplasmic reticulum membranes with an apparent Kd of 3.8 X 10(-5) M. The binding of ANS- had no effect on Ca2+ transport or Ca2+-dependent ATPase activity. EGTA, by binding endogenous Ca2+, increased the fluorescence intensity of bound ANS- by 10-12%. Subsequent addition of ATP, ADP, or Ca2+, in the presence or absence of Mg2+, reversed this change of fluorescence. The binding parameters, as determined by these decreases in fluorescence intensity, were as follows: for ATP, Kd = 1.0 X 10(-5) M, nH = 0.80; for ADP, Kd = 1.2 X 10(-5) M, nH = 0.89; and for Ca2+, Kd = 3.4 X 10(-7) M, nH = 1.8. The binding parameters for ITP and for the nonhydrolyzable analogue, adenyl-5'-yl-beta, gamma-methylene)diphosphate, were similar to those of ATP, but GDP, IDP, CDP, AMP, and cAMP had lower apparent affinities. Millimolar concentrations of pyrophosphate also decreased the fluorescence of bound ANS-, whereas orthophosphate caused a small (2-3%) increase in fluorescence in Ca2+-free media. Vanadate, in the presence of EGTA, decreased the fluorescence of bound ANS-with half-maximal effect at 4 X 10(-5) M. The changes of fluorescence intensity of bound ANS- appear to reflect conformational changes of the (Ca2+, Mg2+)-ATPase, consequent to ligand binding, with the low and high fluorescence intensity species corresponding to the E1 and E2 conformations, respectively. These appear to reflect similar conformational states of the (Ca2+, Mg2+)-ATPase to those reported by changes in intrinsic tryptophan fluorescence (DuPont, Y. (1976) Biochem, Biophys. Res. Commun. 71, 544-550).
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    Properties of the nucleotide binding sites of the Ca²⁺-ATPase of sarcoplasmic reticulum
    (1988) Jeans, David Richard; Berman, M C
    Properties of the nucleotide binding site of the Ca²⁺-ATPase of skeletal muscle sarcoplasmic reticulum have been investigated. The study centred around interaction of the high affinity ATP analog, 2'-3'-0-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate, (TNP-ATP), with the Ca²⁺-ATPase. Defined fractions of the sarcoplasmic reticulum (SR), corresponding to the terminal cisternae (TC) and light SR (LSR), were isolated. The TC were shown to have distinctive morphological characteristics that differ from the LSR. The TC vesicles contained electron dense intravesicular material representative of Ca²⁺ binding proteins, and visible membranous "feet" structures, which are reported to interconnect with the transverse tubule. Functional characterisation of the isolated fractions provided evidence for the predominant localisation of Ca²⁺ release channels in TC, and concentration of Ca²⁺-ATPase molecules in LSR. These conclusions were based on the following observations: (a) decreased Ca²⁺ transport of TC versus LSR; ruthenium red, a Ca²⁺ channel blocker, enhanced Ca²⁺ transport and pumping efficiency in TC, (b) higher Ca²⁺-ATPase activity for LSR in the presence and absence of ionophore, (c) rapid Ca²⁺ efflux from TC which is inhibited by ruthenium red. Of special interest was the characterisation of the TC and LSR with respect to turnover-dependent TNP-ATP fluorescence. Fluorescence observed for TC was approximately 65% of that for LSR. This phenomenon may be attributable to either the decreased Ca²⁺ ATPase content of the TC vesicles or open Ca²⁺ release channels. Hence the TNP-ATP fluorescence characteristics appear to reflect the morphological and functional subspecialisation of the defined SR fractions.
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    Structure and function of sarcoplasmic reticulum isolated from slowly and from rapidly-glycolysing skeletal muscle
    (1975) McIntosh, David Bruce; Berman, M C
    There is evidence that sarcoplasmic reticulum isolated from muscle that has undergone a rapid post-mortem decline in pH has impaired calcium-accumulating ability when compared with that from normal muscle which has a slow rate of pH decline (Greaseret al., 1969a). The enzyme responsible for translocating the cations, namely the ATPase protein, was less affected. The implication is that ATP hydrolysis has been uncoupled from vectorial transfer of calcium through the reticular membrane. This study establishes the quantitative differences in calcium transport and ATPase activity of fragmented sarcoplasmic reticulum from the two muscle sources and has attempted to determine the nature of the diminished efficiency of sarcoplasmic reticular vesicles from muscles of diseased animals. In view of the membrane-bound nature of the pump protein, the influence of the lipid environment on its functional activity was considered and a detailed analysis of the lipids of the sarcoplasmic reticular membrane was carried out. The lipid studies included on analysis of whole muscle since a general derangement of muscle cell membranes is inferred in this disease from the diffusion of proteins and ions out of the muscle cell into the extracellular fluid. In addition, the nature of the lipid-ATPase interaction was examined by observing the effect of temperature on the functional activities of the sarcoplasmic reticulum.