Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hepatocyte and haematopoietic cell contents of the liver of the foetal guinea pig were measured over the latter half of gestation. Hepatocytes represented about 30% of liver volume at mid-gestation and this increased to 70-80% by term; cell volume remained fairly constant until 5-7 days before term, then more than doubled. Haematopoietic cells represented about 5% of liver volume at mid-gestation and this progressively fell to <1% by term. At 75% of gestation hepatocytes and haematopoietic cells were prepared from perfused foetal livers by collagenase digestion. Enzyme activity of the hepatocyte was, without exception, similar to that of the whole liver. In general, enzyme activity in the haematopoietic cells was similar to that in erythrocytes, with relatively low values for aldolase, glycerol 3-phosphate dehydrogenase, phosphoglycerate mutase, enolase, lactate dehydrogenase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, isocitrate dehydrogenase, ;malic' enzyme, glutamate dehydrogenase and aspartate aminotransferase. The haematopoietic cell contribution to total enzyme activity in the foetal liver was usually much less than 10% and could thus not account for the major changes in hepatic enzyme activity over the latter half of gestation. Hepatocytes contained hexokinase isoenzymes I and III, aldolase isoenzymes A and B and pyruvate kinase isoenzymes 1, 2 and 4. The haematopoietic cells contained hexokinase isoenzyme I and two additional bands of activity with slightly greater mobility, aldolase isoenzyme A and pyruvate kinase isoenzymes 2 and 4.
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PMID:The distribution of enzyme and isoenzyme activities between parenchymal and haematopoietic cells in the liver of the foetal guinea pig. 43 88

Hepatocytes were isolated by collagenase perfusion of livers from rats that had been allowed access to a carbohydrate-rich diet or laboratory chow or had been deprived of food 48h before use. By incubation with l-[4,5-(3)H]leucine and precipitation with anti-(L-type pyruvate kinase) sera the rates of synthesis and degradation of L-type pyruvate kinase were measured in freshly prepared cells and hepatocytes maintained in monolayer culture for up to 5 days. Hepatocytes from carbohydrate-rich-diet-fed rats synthesized more L-type pyruvate kinase than did cells from chow-fed animals, which in turn synthesized more than cells from 48h-starved rats. Hepatocytes maintained in culture for up to 5 days synthesized L-type pyruvate kinase at similar rates to freshly prepared cells. The degradation of [(3)H]leucine-labelled L-type pyruvate kinase was shown to be biphasic. A phase with t((1/2)) (half-time) 4.9h and a duration of 8-10h was followed by a phase with t((1/2)) 79.2h. Cells from chow-fed and carbohydrate-rich-diet-fed rats showed similar patterns of degradation of L-type pyruvate kinase. The addition of 2mm-fructose and 0.1mum-insulin to the culture medium increased the t((1/2)) of the rapid phase to 12h in cells isolated from carbohydrate-rich-diet-fed rats, but not in cells from chow-fed rats. The secondary, slower, phase of degradation remained unaffected. The degradation of fructose 1,6-bisphosphatase and total cell protein followed first-order kinetics. The half-life of fructose 1,6-bisphosphatase was 41.0h in cells from chow-fed animals and 48.5h in cells from carbohydrate-rich-diet-fed donors. Fructose and insulin did not affect the rate of enzyme degradation. We propose that there is a role for protein catabolism in the short-term and long-term control of L-type pyruvate kinase concentration.
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PMID:The turnover of L-type pyruvate kinase in cultured rat hepatocytes. 628 20