Biochimica et biophysica acta
-
Biochim. Biophys. Acta · Jun 1978
Polysome activity in relation to growth and protein starvation in brains and hearts of cultured early chick embryos.
In previous studies, brains but not hearts of intact early chick embryos were found to be sensitive to protein starvation. In this study, the in vitro protein synthetic activity of polysomes isolated from brains was found to be greater than those isolated from hearts. ⋯ In addition, neither the stability of isolated polysomes nor ribosome-associated ribonuclease activity appeared responsible for the differences observed in polysome synthetic activities. In direct relationship to the differential sensitivity of brains and hearts to starvation observed in the intact embryo, ribosomes isolated from brains of both growing and starved embryos were more readily degraded during in vitro incubation than those from hearts.
-
Biochim. Biophys. Acta · Apr 1978
Comparative StudyPolymorphism in fowl serum albumin. VII. Distribution and activity of free and membrane-bound polysomes in developing fowl liver.
The quantity and activities of membrane-bound and free polysomes in livers from chick embryos at successive stages of development were compared in cell-free protein-synthesizing systems. Membrane-bound polysomes increased 2-fold between 8 and 18 days of development, while total ribosome content remained constant. ⋯ Serum albumin biosynthesis occurred primarily on membrane-bound polysomes. With liver development, increased secretion of serum proteins may be correlated with synthesis of serum albumin on increasing numbers of membrane bound polyribosomes.
-
Biochim. Biophys. Acta · Apr 1978
Purification and characterization of a long chain, fatty-acid-binding protein supplying the mitochondrial beta-oxidative system in the heart.
A fatty-acid-binding protein with a molecular weight of approximately 12 000 was purified from rat heart and the binding investigated by electron spin resonance. The stearic acid bound to the protein was found to be transferred to the mitochondrial beta-oxidative system, suggesting a role as transcytoplasmic fatty acid carrier for this protein. For the first time a physiological cytoplasmic protein was used as a carrier supplying the mitochondrial beta-oxidative system. A new mechanism of action is proposed to explain the control exerted by this type of protein in some membrane-linked enzymatic processes.
-
Biochim. Biophys. Acta · Feb 1978
The relative contribution of propionate, and long-chain even-numbered fatty acids to the production of long-chain odd-numbered fatty acids in rumen bacteria.
1. The relative contribution of propionate, and long-chain even-numbered fatty acids to the production of long-chain odd-numbered fatty acids in six pure cultures of rumen bacteria were studied, using single and double isotope procedures. 2. ⋯ The incorporation of propionate into odd-numbered fatty acids was markedly reduced in the presence of palmitate, or stearate. 5. The significance of the operation of alpha-oxidation is discussed in relation to the energy conservation in rumen bacteria.
-
Biochim. Biophys. Acta · Apr 1977
Odd-and even-numbered fatty acids. Their contrasting behavior in normal and fowlpox virus-infected epithelium.
Upon infection with fowlpox virus, the amount of odd-numbered fatty acids in chick scalp epithelium shows a significant decrease compared with control values. This effect begins quite early and progresses throughout the period of infection. Individual members of the odd-numbered family (C15--C27 inclusive) were quantitatively related to the group as a whole during most of the infection. ⋯ In assays for fatty acid synthetase activty, both [14C] acetyl-CoA and [14C]-propionyl-CoA were used as initial acceptors. The specific activities of preparations from infected scalp were similar to those of control preparations with both substrates. These results suggest that there is no decline in the ability to utilize propionate for fatty acid synthesis in infected epithelium.