Biomedical subjects

S Fazekas

Publications and source records attributed to S Fazekas.

27 records · Page 2Linked to original sources

PubMed1985

Composition of amino acid phosphates in phosphorylated G-actin of rabbit skeletal muscle.

In our experiments the phosphorylation of actin was studied. Similar investigations have been published in the literature, however very long incubation time was applied in these studies and even so a low incorporation of phosphate concentration was found. The present phosphorylation experiments were performed using short incubation periods as usual in our myosin investigations and was characterized by an unexpectedly high phosphate saturation. We suggest that in suitable incubation medium the nucleotide- and phosphate-free actin prepared by using phosphate- and ATP-free solutions takes only 1 minute to become saturated, while in its peptide chain a N-P bond type acid labile phosphate is formed. On maximum saturation 9 M P-arginine, 0.4 M P-histidine and some minor phosphorylated derivatives can be observed. After a longer period of incubation, with a lower incorporation of phosphate (3 mol P) a more stable phosphorylated actin is formed. As a result of preparation and gel filtration a dimer and a monomer form of actin can be obtained. Both of them exhibit the basic properties of actin (polymerization, myosin-ATPase activation) and the phosphate incorporation described in this paper.

Actins↗

PubMed1982

Isolation, properties and P content of the human brain myosin.

KCl-, and NaCl-myosins were prepared from different parts of the central nervous system (CNS). Throughout these experiments P and lipid contents were higher in NaCl-myosins than in KCl-preparations. Both KCl-, and NaCl-myosins have increased lipid and P contents compared with skeletal muscle myosins. When the specimens were separated by a molecular sieve, it was found by chromatographic technique on Sepharose 4B column that the cerebral and cerebellar myosins were composed of two fractions of different molecular mass while the brain stem and spinal cord myosins revealed only a single peak. The myosin fractions' Ca-ATPase activity could be augmented by rabbit muscle actin. The myosin preparations developed filamentous systems and aggregates which could be shown by scanning electron microscopy. All the CNS-myosin preparations could be phosphorylated; however, they were saturated to a different degree and were influenced by the presence or absence of serotonin. The kinetic studies revealed that the phosphate saturation of the brain stem, cerebellar and cerebral myosins depended on the ATP concentration and incubation time. The alkaline hydrolysates of lipid-free human brain myosin preparations contained amino acid phosphates, P-Arg, P-Lys and P-His in different amounts depending on their sources. In response to a phosphorylating mixture only the amount of P-Arg was elevated in the cerebral myosins, P-Arg and P-His in the brain stem preparations, and P-Arg, P-His and the amounts of unidentified compounds in the cerebellar ones.

Adult↗

PubMed1981

Preparation and purification of myosin from human tracheal smooth muscle.

NaCl myosin was prepared from the annular smooth muscles of human bronchus. About 7 mg of gel filtered myosin was gained from 8 g minced tracheal muscle of the younger subject. The yield from the older (74-year old) subject was only 30% of that from the younger subject, even though the starting material was more (12 g minced tissue). Tracheal myosin contains P lipid in considerable amount; P lipids account for some 28% of the total phosphate content of the myosin, and even more (50-55%) in the case of the older subject. The preparation could be phosphorylated only in the presence of CAMP and PGF2 alpha, respectively. Cu2+ treatment liberated less phosphate when compared with myosin preparations from other smooth muscles; however, the majority of the phosphate bonds underwent hydrolysis upon the effect of KOH. The reactions specific for amino acids, and also other observations allow the conclusion that the majority of covalently bound phosphate is present in an ester-type bond. Lysine-vasopressin, and also diethylpyrocarbonate successfully protect the P content of myosin from the hydrolysis inherent to incubation.

Adenosine Triphosphate↗

PubMed1980

Purification and phosphate content of slow-twitch human myosin and its possible role in the maintenance of muscle function.

In the present study the phosphate content of a slow-twitch human muscle myosin was investigated and compared with other myosins. It was found that, similar to myosin of the skeletal muscle of the rabbit, the total and labile phosphate content of this human myosin varied depending on the load previously imposed on the muscle. The labile phosphate content thought to be important in the course of contraction ranged between 4 and 8 mol, which might be explained by the different load applied on the preparations in study. These data were compared with those obtained in a fast-twitch human myosin and the changes in its phosphate content appeared to support the hypothesis put forward on the basis of recent studies on slow-twitch myosin.

Adult↗

PubMed1977

Surgical drainage of a submandibular air sac in an orangutan.

Continuous enlargement of a submandibular air sac was observed in a 7-year-old female orangutan. The animal was treated with tetracycline orally prior to administering phencyclidine and establishing surgical drainage. The incision into the air sac remained patent for 5 days and the cutaneous wound healed 2 weeks later.

Animals↗

PubMed1973