Biomedical subjects

W Huth

Publications and source records attributed to W Huth.

31 records · Page 2Linked to original sources

PubMed1978

Acetyl-CoA acetyltransferase from bovine liver mitochondria. Molecular properties of multiple forms.

Bovine liver mitochondrial acetyl-CoA acetyltransferase (acetyl-CoA:acetyl-CoA C-acetyltransferase, EC 2.3.1.9) has been obtained in three forms designated transferase I, A and B on the basis of their elution positions from chromatography on phosphocellulose. All forms have been shown to have a molecular weight of about 152 000, each being composed of four similar subunits. Amino acid analysis of transferase A and B, the two major forms, revealed a close relationship between both forms with almost identical amino acid composition and arginine as N-terminal residue. The three transferases differ with respect to their redox state and their multiplicity of forms with isoelectric points of 6.9, 7.5 and 8.8, into which the transferases I and A were spontaneously transformed upon isoelectric focusing or rechromatography on phosphocellulose. Transferase B represents a stable enzyme form with an isoelectric point of 8.8. Although the redox state of transferase B can be adjusted to that of transferase A still a difference in charge and in the multiplicity of forms exists, thus indicating different protein states.

Acetyl-CoA C-Acetyltransferase↗

PubMed1978

[Psychic disturbances in adopted children--an overview of the postiion of clinical research].

Empirical studies on the psychopathology of adoptees are summarized and discussed with regard to the possibility of a relationship between adoption and psychic disturbances. The results leave the question open as to whether adoptees are more prone to psychic disturbances than other individuals. Those under treatment do not seem to be more severely disturbed than others. Whereas however the adoptees display more disturbances in their social behavior rather than neurotic disturbances, the relationsship is reversed in the population of the non-dopted. The causes seem to lie in the conditions in early childhood and in the experience of being adopted itself.

Adoption↗

PubMed1975

On the mechanism of ketogenesis and its control. Purification, kinetic mechanism and regulation of different forms of mitochondrial acetoacetyl-CoA thiolases from ox liver.

1. Two mitochondrial forms of acetoacetyl-CoA thiolases designated as enzyme A and enzyme B were crystallized from ox liver. They could be shown to be homogenous by polyacrylamide gel electrophoresis. 2. In direction of acetoacetyl-CoA cleavage enzyme A shows a double competitive substrate inhibition when acetoacetyl-CoA is varied at different fixed CoA concentrations. With enzyme B a parallel kinetic pattern is obtained when acetoacetyl-CoA is varied at different fixed CoA concentrations. In direction of acetoacetyl-CoA synthesis both enzymes show linear reciprocal plots of initial velocities against acetyl-CoA concentrations in absence of CoA. These initial velocity kinetics in the forward and in the reverse direction are in accordance with a ping-pong mechanism of reaction for both enzymes involving an acetyl-S-enzyme as intermediate. 3. Under saturating concentrations of substrate, the ratios of acetoacetyl-CoA synthesis/aceto-acetyl-CoA cleavage is 0.31 for enzyme A and 0.08 for enzyme B. The maximum velocity in direction of acetoacetyl-CoA synthesis of enzymes A and B are 0.43 mumol X min-1 X unit thiolase-1 and 0.10 mumol X min-1 X unit thiolase-1, respectively. 4. Both enzymes show nearly the same affinity for acetyl-CoA. The Km values are 91 muM (enzyme A) and 80 muM (enzyme B). 5. Coenzyme A and acetoacetyl-CoA both act as inhibitors in direction of acetoacetyl-CoA synthesis: coenzyme A is a nonlinear competitive inhibitor of both enzymes. Acetoacetyl-CoA exerts a negative cooperativity on enzyme A (nH = 0.63) and is a competitive inhibitor for enzyme B (Ki = 1.6 muM). 6. The catalytic and regulatory properties of the acetoacetyl-CoA thiolases A and B are discussed in terms of their proposed role in regulating ketogenesis. Intracellular fluctuations of acetoacetyl-CoA/3-hydroxybutyryl-CoA ratios, resulting in a suspension of inhibition of both enzymes at high NADH/NAD ratios, are postulated as a control mechanism of ketogenesis in addition to mechanisms already known.

Acetyl-CoA C-Acetyltransferase↗

PubMed1974