The phosphotransferase system of human central-nervous-system myelin was investigated. Evidence obtained indicated the presence of at least two different phosphotransferase systems (cyclic nucleotide-dependent and -independent) in myelin, which were found to be firmly associated with the membrane. The cyclic AMP-dependent kinase of myelin and white-matter cytosol preferentially phosphorylated certain histone fractions and displayed only modest activity with basic protein as substrate. On the other hand, the cyclic nucleotide-independent system showed specificity toward basic protein. Its activity was not only dependent on Mg2+ but it was greatly enhanced by this bivalent cation. Whereas the cyclic nucleotide-dependent kinase could be extracted with buffers containing Triton X-100, the bivalent cation-regulated kinase resisted solubilization from myelin under these conditions.

Normal and abnormal breast samples of women were analyzed for multiple molecular forms of lactate dehydrogenase and glucose 6-phosphate dehydrogenase, using acrylamide disc gel electrophoresis and specific enzyme staining techniques for separation and quantitation. Infiltrating ductal carcinomas demonstrated a significant increase (three-to six-fold) in the proportion of LDH-5 compared to samples of normal breast, fibrocystic disease and fibroadenoma, indicative of a shift toward the muscle-type lactate dehydrogenase in neoplasia. For glucose 6-phosphate dehydrogenase, carcinomas were found to contain increased proportions of the fastest migrating species, G6PD-I. Total enzyme activity/mg DNA was elevated in neoplastic tissues. Little or no alteration in isoenzyme profiles could be related to menopausat status of the patient.Cancer 37:1825-1830, 1976. ULTIPLE MOLECULAR FORMS O F ENZYMESM have been examined in normal and cancerous tissues for several years.lB,18 T h e development of techniques, such as acrylamide disc gel electrophoresis has facilitated these investigations, since quantitation, or at least semi-quantitation, can be accomplished with relative ease. Thus, by utilizing specific enzymatic localization procedures, the resultant gels can be scanned in a spectrophotometer and the areas under each discrete peak can be estimated with a good degree of accuracy.One of the first studies of human breast cancer €or lactate dehydrogenase (LDH) isoenzymes was performed by Goldman, Kaplan and Ha11,S in which it was found that carcinomas of the breast contained a greater amount of the muscle-type LDH than did samples of normal breast. Studies of experimental mammary tumors in rats,ll some of which were conducted in our laboratory,20 indicated that these neoplasms demonstrated a relatively high proportion of the muscle-type L D H (LDH-5 and LDH-4), although it was also reported that during pregnancy and lactation, the rat mammary gland showed an increase in the proportion of Along similar lines, interest in multiple molecular forms of glucose 6-phosphate dehydrogenase (GGPD) was stimulated by our finding that both transplantable and carcinogeninduced rodent mammary tumors demonstrated GGPD species that were responsive to hormonal manipulation of the host.21.22 I n the case-of mammary carcinoma of BALB/c mice, and its preneoplastic lesion, the hyperplastic alveolar nodule, a species of GGPD appeared to occur that was not present in significant amounts in normal mammary gland.13It therefore seemed logical that the multiple molecular forms of LDH and GGPD be examined in a large series of human carcinomas and that such results be compared to data obtained from a study of fibrocystic disease and fibroadenoma, two nonmalignant but proliferative diseases of women. I n addition, normal 1825

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Certain selected enzymes of carbohydrate metabolism were measured in samples of endometrium and myometrium from women who were premenopausal or postmenopausal. In addition, a number of samples of leiomyoma were obtained and assayed. Activities of several enzymes were higher in endometrium from premenopausal women compared to those in postmenopausal women; activities in myometrium were similar regardless of menopausal status. The activities of G6PD, ICD and GPI appeared to be lower in leiomyoma samples versus myométrial samples from premenopausal women; however, these differences were not apparent when enzyme activity was expressed per milligram protein.