Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.13 (aldolase)
 3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 28 dogs the distal articular cartilage of the femur was removed and the regenerating articular surface on the 70th postoperative day was studied histochemically for hexokinase, glucose-6-phosphatase, phosphohexose-isomerase, fructose-1, 6-diphosphatase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, lactate dehydrogenase isoenzymes, phosphoglucomutase, phosphorylase, glycogen synthetase, UDP--glucose dehydrogenase, and UDP-glucuronic acid-4-epimerase. The articular surface consisted of fibrous tissue and of cartilage islets. The latter contained cells differentiating into cartilage and young chondrocytes. The glycolytic enzymes reacted positively in the regenerative articular surface. Enzyme activities were higher in the cells (particularly the chondroblasts and young chondrocytes) of the cartilage islets than in the connective tissue. In the cells differentiations into cartilage, beside the LDH isoenzymes characteristic of glycolysis, a significant LDH1 and LDH2 activity was observed. At the same site the presence of fructose-1, 6-diphosphatase-activity could be assumed, but there was no glucose-6-phosphatase activity. Glycogen synthesis proceeded in the cells of the cartilage islets and UDP-glucuronic acid-4-epimerase activity was observed in the differentiated cells. UDP-glucose dehydrogenase activity was positive in every section of the articular surface.
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PMID:Studies on cartilage formation. XX. Histochemical investigation of some enzymes of glycogen metabolsim in regenerative articular surfaces. 18 10

We have previously found that the restoration of cartilage matrical proteoglycans is preceded by markedly increased activity of uridine diphosphoglucose dehydrogenase (UDPGD), an enzyme directly associated with glycosaminoglycan (GAG) synthesis, and by increased activity of enzymes of the major energy yielding pathways (glucose-6-phosphate dehydrogenase (G6PD), glyceraldehyde-3-phosphate dehydrogenase (GAPD) and succinate dehydrogenase (SDH)). We did not find an increase in lactate dehydrogenase (LDH). In the present longitudinal study of rabbits (from 5 weeks to 42 months of age), we looked for age related changes in the activity of these enzymes in auricular chondrocytes, as well as for collagen and GAG content. Collagen content (micrograms/wet weight) increased up to 12 months and remained stable; total GAG content (micrograms/wet weight) reached its maximal value at growth and then declined gradually, reducing the GAG/collagen ratio dramatically from 36 to 8. At any age LDH was two to three times more active than either G6PD, aldolase, or GAPD. SDH and UDPGD activities were even lower. The age related changes varied: (1) LDH and GAPD were stable and did not change with either growing or aging; (2) G6PD and aldolase reached their maximal activity at 3-9 months, followed by a sharp drop at 12 months. G6PD remained stable, while aldolase continued to decline, although more slowly; (3) Maximal activity of SDH and UDPGD was measured at 5 weeks. Thus, the changes in enzyme activity in chondrocytes with age were specific for each enzyme. The significant decline in G6PD, aldolase, the rate-limiting enzymes of the pentose shunt and classic glycolysis, and SDH markedly reduced the ability of chondrocytes to generate energy.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential decline of rabbit chondrocytic dehydrogenases with age. 778 68