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Biomedical subjects

M Chulavatnatol

Publications and source records attributed to M Chulavatnatol.

8 recordsLinked to original sources
PubMed1979

Autoproteolysis in human seminal plasma under acidic condition.

The existence of both neutral and acidic proteases in human seminal plasma suggests a possible autohydrolysis of the proteins in the fluid. By means of polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the autoproteolysis in human seminal plasma was shown to occur at pH 3.5 but not at pH 5.0--7.5 conditions. At pH 3.5, most proteins of large molecular weight, except one of 28,000 daltons, were completely hydrolyzed into peptides of 13,000 daltons or smaller. The autoproteolysis was due to the action of the acidic protease since it can be blocked by 1 mM of p-bromophenacyl-bromide or 1,2-epoxy-3-(p-nitrophenoxy) propane, the specific inhibitors of the acidic protease.

Humans↗
PubMed1977

Stabilization of adenylate energy charge and its relation to human sperm motility.

The adenylate energy charge of human ejaculated spermatozoa was studied when the sperm motility was perturbed by varying pH, prolonged incubation, and caffeine. Between pH 8 and 9, which was optimal for the sperm motility, the energy charge was in the physiological range of 0.8 to 0.9. Above pH 9, the mobility, ATP content, and adenine nucleotide pool declined rapidly but the energy charge was maintained slightly below 0.8. Below pH 8, the motility also dropped drastically, but the ATP, nucleotide pool, and energy charge fell only slightly. Prolonged incubations of the spermatozoa decreased the motility, ATP, and nucleotide pool. However, the energy charge would remain above 0.6. Caffeine stimulation of the motility caused a rapid fall of ATP and the reduction of the physiological energy charge by 0.2 unit, unless glucose was added. Imidazole which reduced the caffeine-stimulated motility did not alter the physiological energy charge of the spermatozoa. The study showed that the spermatozoa could maintain the energy charge above 0.6 under stress.

Adenine Nucleotides↗
PubMed1977

Acid protease and its proenzyme from human seminal plasma.

An acid protease, with an optimum pH of 2.5, exists in seminal plasma in a proenzyme form. In acidic pH, the proenzyme is converted into the active form, resulting in the release of small molecular weight peptide. The extent and rate of proenzyme-active enzyme conversion is absolutely dependent on pH. Between pH 5 and 2, as the pH is lowered, the extent of conversion increases and reaches a maximum between pH 3 and 2. The kinetics of activation shift from first-order between pH 2 and 4 to more complexity with a lag period between pH 4.5 and 5. Under physiological conditions, the proenzyme might be activated by coming into contact with acidic vaginal fluid during ejaculation. The acid protease can hydrolyze the cervical mucus protein.

Amino Acids↗
PubMed1976

Activation of proenzyme of acidic protease from human seminal plasma.

The kinetics and the extent of the conversion of the proenzyme into the active acidic protease (EC 3.4.23.--) of human seminal plasma were dependent on acidic pH. Between pH 2 and 4, the initial rate of the activation was first-order with respect to the proenzyme. Between pH 4.5 and 5, the rate deviated from the first-order with an initial lag period which can be abolished by adding an excess amount of the acidic protease or pepsin. The extent of the activation was complete between pH 2 and 3 and became incomplete between pH 4 and 5. Addition of the acidic protease or pepsin did not alter the extent of the activation at the high pH values. According to the chromatographic profile on a Sephadex G-75 column, the activation products (namely active acidic protease and an activation peptide) obtained at pH 3 and those obtained at pH 4.5 were identical. The molecular weight of the activation peptide obtained at pH 3 was 6900; its amino acid composition was analyzed and compared with those of the proenzyme and the acidic protease. Remarkable similarity between the amino acid composition of the acidic protease and that of human pepsin was observed. In the presence of an excess amount of hemoglobin, the conversion of the proenzyme was self-activated and showed an initial lag period. Addition of acidic protease did not change the rate of self activation or the lag period.

Amino Acids↗
PubMed1976

Changes in surface ATPase of rat spermatozoa in transit from the caput to the cauda epididymidis.

Rat spermatozoa from the cauda epididymidis were found to have a lower activity of the surface ATPase than the spermatozoa from the caput region. The enzyme from spermatozoa of both regions had the same Michaelis constant (Km) for ATP of 5 X 10(-4) M. It was partly inhibited by ouabain and fluoride, but strongly inhibited by Cu2+, Zn2+,p-chloromercuribenzoate, 8-anilino-1-naphthalenesulphonate Triton X-100, Lubrol-PX, urea, guanidine hydrochloride, sodium dodecyl sulphate and glycerylphosphorylcholine. The enzyme of the spermatozoa from the cauda epididymidis was more sensitive to inhibition by ouabain and fluoride but less sensitive to inhibition by Cu2+ than that of the cells form the caput region. The Arrhenius plot of the temperature dependence of enzymatic activity varied for the cells from the caput and cauda epididymidis. The differences in the enzyme properties of spermatozoa from the two regions of the epididymis suggested that the decline in the activity during epididymal maturation may reflect changes in the lipids and sulphydryl groups of the sperm membrane.

Adenosine Triphosphatases↗
PubMed1975

Acidic protease from human seminal plasma. Purification and some properties of active enzyme and of proenzyme.

A procedure to purify to homogeneity the active form as well as the proenzyme form of the acidic protease of human seminal plasma is described. This involved precipitation with ammonium sulfate, chromatography on diethylaminoethylcellulose, Sephadex G-200, and Sephadex G-100. The molecular weights of the active form and of the proenzyme were determined by electrophoresis and gel filtration to be 35,000 and 42,000, respectively. The proenzyme was more stable than the active form in alkaline solution and can be converted into the active enzyme under acidic conditions. The active form of the acidic protease can hydrolyze hemoglobin, N,N'-dimethylcasein, N-acetyl-L-phenylalanyl-L-diiodotyrosine, and N-benzyloxycarbonyl-L-glutamyl-L-phenylalanine, but cannot hydrolyze bovine serum albumin, ovalbumin, N-benzyloxycarbonyl-L-glutamyl-L-tyrosine. The active form was also inhibited by p-bromophenacyl bromide and 1,2-epoxy-3-(p-nitrophenoxy)propane.

Animals↗