Enzymes Aldolase Research Articles

Improved detection of Duchenne muscular dystrophy heterozygotes using discriminant analysis of creatine kinase levels.

We have assessed the sensitivity and specificity of tests to detect carriers of Duchenne muscular dystrophy by use of three serum enzymes (creatine kinase, pyruvate kinase, and aldolase) and discriminant analysis in 21 obligate heterozygotes and 28 normal controls. We found no significant age effects on enzyme levels. Each enzyme level considered separately was significantly higher in heterozygotes. Use of logs improved discrimination, and log CK was sufficient by itself as a discriminant (that is, addition of other enzymes did not significantly improve discrimination). We present procedures to generate posteriori probabilities for genetic counselling that incorporate prior probabilities and enzyme levels. Our results show both improved sensitivity (90%) and specificity (86%).

Multivariate analysis of plasma enzyme profiles in severe head injury.

We followed the changes in the activities of four enzymes (aldolase, aspartate aminotransferase, creatine kinase, and lactate dehydrogenase) in plasma for four days after head injury. The progression of the changes differs significantly between survivors and nonsurvivors. Stepwise discriminant analysis, involving the four enzymes, allowed us to divide 81 to 92% of head-injured patients (n = 280 selected without conscious bias) correctly into the two groups as early as 72 h after trauma. Most of the patients who were misclassified according to our biochemical criteria had received phenobarbital for sedation. Valuable prognostic information in head injury evaluation may thus be obtained by daily determination of enzymatic activities of these four enzymes.

Regulation of concentrations of glycolytic enzymes and creatine-phosphate kinase in “fast-twitch” and “slow-twitch” skeletal muscles of the chicken

The distinctive contractile and metabolic characteristics of different skeletal muscle fiber types are associated with different protein populations in these cells. In the present work, we investigate the regulation of concentrations of three glycolytic enzymes (aldolase, enolase, glyceraldehyde-3-phosphate dehydrogenase) and creatine-phosphate kinase in “fast-twitch” (breast) and “slow-twitch” (lateral adductor) muscles of the chicken. Results of short-term amino acid incorporation experiments conducted both in vivo and with muscle explants in vitro showed that these enzymes turnover at different rates and that aldolase turns over 2 to 3 times faster than the other three enzymes. However, these differences in turnover rates were difficult to detect in long-term double-isotope incorporation experiments, presumably because extensive reutilization of labeled amino acids occurred during these long-term experiments. Mature muscle fibers synthesize these four cytosolic enzymes at very high rates. For example, 11 to 14% of the total labeled leucine incorporated into protein by breast muscle fibers was found in the enzyme aldolase. Results of short-term amino acid incorporation experiments also showed that the relative rates of synthesis of the three glycolytic enzymes were about fourfold higher in mature “fast-twitch” muscle fibers than in mature “slow-twitch” ones while the relative rates of synthesis of creatine-phosphate kinase were similar in the two fiber types. The relative rates of synthesis of these four enzymes and cytosolic proteins in general were found to be very similar in immature muscles of both types. More profound changes in the relative rates of synthesis of major cytosolic proteins, including the glycolytic enzymes, occurred during postembryonic maturation of fast-twitch fibers than occurred during maturation of slow-twitch fibers. Our work demonstrates that (1) the synthesis of creatine-phosphate is independently regulated with respect to the synthesis of the glycolytic enzymes in muscle fibers; and (2) the approximate fourfold higher steady-state concentrations of glycolytic enzymes in fast-twitch muscle fibers as compared with slow-twitch fibers are determined predominantly by regulatory mechanisms operating at the level of protein synthesis rather than protein degradation. Our demonstration that more profound changes in the relative rates of synthesis of major cytosolic proteins occur during maturation of fast-twitch fibers as compared with slow-twitch fibers is discussed in terms of the mode(s) of fiber-type differentiation proposed by others.

Estimation of physiologically active zinc in maize by biochemical assay

The enzymes ribonuclease, aldolase and carbonic anhydrase were evaluated as biochemical assays for physiologically active zinc in maize. Seedlings were cultured for 14 or 30 days on a black-earth soil with factorial combinations of phosphorus and zinc fertilizers so as to produce in the leaves varying levels of active zinc at a constant level of total zinc. Enzyme activity was correlated with plant growth, leaf nutrient composition and the occurrence of visual symptoms of zinc deficiency.

Positive and negative adaptation of muscle enzymes in aging mice subjected to physical exercise

CWI mice at the age of 6, 22 and 27 months were subjected to a controlled physical training program for 5 weeks. Changes in specific activity of the enzymes aldolase, superoxide dismutase and catalase of the total hind-leg muscle tissues were followed. During the training period, specific activities of these muscle enzymes exhibited an adaptive increase in the 6 and 22 months groups. In senile (27 months) mice, however, enzyme activities decreased as a consequence of the physical challenge. Total body weight was not altered under these conditions. Immunotitration of extracts with anti-aldolase and anti-creatine kinase antibodies showed no significant differences, indicating that there was no accumulation or disappearance of faulty proteins during aging and physical exercise.

Studies on myo-inositol-1-phosphate synthase from Lilium longiflorum pollen, Neurospora crassa and bovine testis Further evidence that a classical aldolase step is not utilized

myo-Inositol-1-phosphate synthase (1 l- myo-inositol-1-phosphate lyase (isomerizing), EC 5.5.1.4.) preparations purified from the pollen of Lilium longiflorum, and from Neurospora crassa have been incubated with d-[5- 18O]-glucose -6-P and the myo-inositol which was formed was analyzed for retention of 18O. In each case, the isotope of oxygen was incorporated into the inositol without loss. If a Schiff base had formed at the 5-position of the [ 18O]glucose -6-P , the isotope should have been released to the incubation medium. Supporting evidence that no Schiff base is formed at the 5-position, or at any other position, was obtained by incubation of the enzymes in media enriched with H 2 18O. If a Schiff base were formed and hydrolyzed, the regenerated carbonyl should become enriched to the level of the medium as reflected by the isotope content of the inositol product. In no case did the product inositol have this degree of enrichment. These data exclude consideration of a Class I aldolase mechanism for these enzymes. The Lilium enzyme is unaffected by EDTA to a concentration of 100 mM. The bovine enzyme is similarly uninhibited by EDTA to a concentration of 50 mM. The Neurospora enzyme has previously been shown to be inhibited by these levels of EDTA and to be activated 2-fold by 2 mM Mg 2+, however, extensive dialysis against EDTA does not eliminate the metal independent activity of the enzyme. In the present study, we have found that divalent metals show a range of stimulation/inhibition with the Lilium and the bovine enzymes, however, neither enzyme is dependent on the metals. Thus, we suggest that these enzymes are not Class II aldolase enzymes either. It is, therefore, possible that the myo-inositol-1-phosphate synthase from these species has an aldol step in the enzymatic pathway which is of neither classical aldolase type.

884 GLYCOLYTIC ENZYMES IN PREMATURE INFANTS ON THE FIRST DAY OF LIFE

Prior studies of RBC glycolytic enzymes in term infants on the first day of life have revealed elevated levels of phosphoglycerate kinase (PGK) and enolase (ENO) and decreased activity of phosphofructokinase (PFK) when compared to both RBC's from normal adults and subjects with a RBC population of a similar young mean cell age, as reflected in pyruvate kinase (PK) activity. In the present study, 25 premature infants were studied on the first day of life to determine whether this increase in RBC PGK and ENO and decrease in PFK activities are greater in the preterm infant and vary with gestational age. There were 3 groups: 9 infants 28-30 wks of age; 9 of 31-33 wks and 7 of 34-36 wks. The age-dependent enzymes PK, hexokinase and aldolase were higher in premature infants than term infants indicating a RBC population of a younger mean cell age. The mean activities of both PGK and ENO were also higher in the premature infants than in term infants but did not differ significantly between 28-30 wks to 34-36 wks. Mean PFK activity, however, was higher, not lower in premature infants than in term infants. In contrast to term infants, PFK activity correlated well with the age-dependent enzyme, PK (r=0.73; p<0.001). Thus, it appears that the young mean RBC population present in the premature infant on the first day of life significantly influences PFK activity, resulting in higher levels than those anticipated at such a young gestational age.

Glycolytic enzymes from human autoptic brain cortex: Normal aged and demented cases

The activities of glycolytic enzymes were determined in human autoptic temporal lobes from patients with different forms of dementia. For some enzymes (hexokinase, phosphofructokinase and phosphoglycerate mutase) the effect seen in dementia can be regarded as an intensification of the normal ageing effect. For other enzymes (aldolase, phosphoglucose isomerase, triosephosphate isomerase and lactate dehydrogenase) no changes in enzyme activities corresponding to those found in dementia are observed in the normal ageing process. These effects are most pronounced in the non-vascular Alzheimer cases. With the exception of triosephosphate isomerase and lactate dehydrogenase, enzyme activity is also reduced in bronchopneumonia. The effects of dementia and bronchopneumonia on the activities of glycolytic enzymes in human autoptic brain tissue are often difficult to distinguish.

76] Dihydroneopterin aldolase from Escherichia coli

This chapter discusses the preparation, purification, and properties of dihydroneopterin aldolase(H 2 -neopterin aldolase) enzyme. In assay method for preparation, the reaction is the removal, as glycolaldehyde, of two carbons of the three-carbon side chain of HE-neopterin. The product, glycolaldehyde, is not adsorbed to activated charcoal, whereas the other product, H 2 -pterin-CH 2 OH, and the residual unreacted substrate, H 2 -neopterin, are both adsorbed. Incubation of the enzyme, with H 2 -neopterin, labeled with tritium on carbon-3 of the side chain, followed by the measurement of the amount of radioactivity not adsorbed to activated charcoal (Darco G-60), is a measure of the amount of glycoaldehyde produced. The molecular weight of H 2 -neopterin aldolase is estimated at 100,000 by comparison of its migration during electrophoresis on SDS polyacrylamide gel with the migration of standard proteins. The pH optimum of the enzyme is at pH 9.6. The products of its action have been identified as H 2 -pterin-CH 2 OH and glycolaldehyde. The formation of products is linear, with incubation time up to 80 min, with the use of the purified enzyme (through the DEAE-cellulose step). The reaction is not reversible.

Localization and membrane association of aldolase in human erythrocytes

A study has been carried out on the association of aldolase with the human erythrocyte membrane. It has been shown that the conditions employed during hypotonic hemolysis affect the amount of aldolase that remains bound to the cell membrane. Thus, the in vivo nature of this binding cannot be ascertained by this technique. Therefore, a method has been developed in which aldolase is crosslinked with glutaraldehyde to the inner surface of the membrane in intact red blood cells. Under the specified conditions, over 90% of the intracellular aldolase can be crosslinked to the membrane with less than 10% of the hemoglobin becoming bound. These results suggest that the localization of aldolase in situ is on or near the inner surface of the membrane. The amount of aldolase bound to the membrane following crosslinking can be decreased by preincubating the cells with cytoskeletal agents such as cytochalasin B, colchicine, and vinblastine sulfate. The in vitro binding of aldolase to the purified spectrin-actin and F-actin complexes was studied. Aldolase bound both complexes very tightly ( K D ≅ 10 −9 m) and this binding could be inhibited by cytochalasin B, but not by colchicine. A competition binding study was carried out to determine if the binding of aldolase to F-actin involved specific interactions. Neither bovine serum albumin nor cytochrome c significantly inhibited the binding of aldolase to F-actin when each was present at equimolar concentrations with aldolase. However, glyceraldehyde 3-phosphate dehydrogenase inhibited aldolase binding to F-actin and when present at equimolar concentrations with aldolase completely blocked the association. The association of aldolase and other glycolytic enzymes with the erythrocyte membrane is discussed and it is postulated that aldolase could be localized in vivo on the inner surface of the membrane by attachment to actin or a spectrin-actin complex.

Regulation of fructose diphosphate aldolase concentrations in skeletal muscles of normal and dystrophic chickens.

We are using the glycolytic enzyme aldolase as a marker to investigate the molecular basis for reduced levels of specific enzyme activities associated with muscular dystrophy. Inbred strains of normal and dystrophic chickens were used as models to study the disease. In the present paper we show that: 1) aldolase & was the only isoenzyme present in normal and dystrophic muscles derived from lto 12-week-old birds; 2) aldolase & isolated from normal and dystrophic breast (“fast-twitch”) muscles were identical molecules on the basis of their electrophoretic, immunological, and catalytic properties; 3) the steady state level of aldolase activity in dystrophic breast muscle was only 40 to 50% of normal; 4) the reduced level of enzyme activity was associated with a corresponding reduction in the level of catalytically active aldolase molecules as determined in immunotitration experiments; 5) the reduced steady state level of aldolase molecules was associated with a corresponding reduction in the relative rate of synthesis of the enzyme in dystrophic breast muscle fibers as determined by short term isotope incorporation experiments conducted in viva and with muscle explants in culture; 6) large increases in synthesis of collagen or other non-muscle proteins by dystrophic muscle samples were not detected by electrophoretic and fluorographic analysis of the radioactive proteins synthesized by muscle slices in culture; 7) in contrast to the situation with “fast-twitch” (breast) muscle, aldolase content and relative rate of synthesis in mature lateral abductor (“slow-twitch”) muscles of dystrophic chickens were found to be essentially normal. We suggest that one of the manifestations of avian muscular dystrophy is a failure of fast-twitch muscle fibers to accurately perform the transition from one enzyme synthetic program to another which normally occurs around the time of hatching.

Cell-density-dependent Changes in the Metabolism of Chloronema Cell Cultures

In the growing chloronema cell suspension cultures of the moss Funaria hygrometrica Hedw., activities of several enzymes have been found to be cell-density-dependent. Cyclic nucleotide phosphodiesterase (cNPDE), nitrate reductase (NR), and protein kinase showed highest activity at a low cell density (1 to 2 milligrams per milliliter) while indoleacetic acid (IAA) oxidase and peroxidase were highest at a high cell density (>10 milligrams per milliliter). 3'-Nucleotidase and the glycolytic enzymes (aldolase, hexokinase, phosphofructokinase, phosphoglucoisomerase, pyruvate kinase, and triose phosphate isomerase) showed no significant dependence on the cell density. Alternatively, if the NR and peroxidase activities were determined as a function of time in batch cultures, their levels were maximal 60 to 70 and 320 hours after subculture, respectively, the corresponding cell densities being 1 to 2 and 23 milligrams per milliliter. The relationship between cell density and NR and peroxidase activities is the same, whether these enzymes are measured in batch cultures during a growth cycle or in the cells cultured at different initial inoculum densities for a constant time. Conventionally enzymic changes have been correlated with growth phases; however, it is felt that the pattern of enzymic activities can also be interpreted as cell-density-dependent.In moss protonema, the dependence of cNPDE, IAA oxidase, and peroxidase on cell density may play an important role in modulating the endogenous levels of IAA and cAMP, both of which regulate the differentiation of specific cell types (Johri and Desai 1973 Nature New Biol 245: 223-224; and Handa and Johri 1976 Nature 259: 480-482).

Metabolism of Red Blood Cells in Chronic Renal Failure

This paper starts a series on red blood cell (RBC) metabolism in patients with chronic renal failure (CRF). The glycolytic enzyme levels and in vitro half-lives of these patients' RBCs were determined. A number of enzymes (hexokinase, glucose-6-phosphate isomerase, fructose-6-phosphate kinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase) showed higher activities than in normal control RBCs. Other enzyme activities were normal. These results were discussed and several possible mechanisms considered. We favour the point of view of a shortened life span of the RBCs in CRF, making the most unstable enzymes of the glycolytic sequence appear increase as compared with normal controls.

Metabolism of RNA-ribose by Bdellovibrio bacteriovorus during intraperiplasmic growth on Escherichia coli

During intraperiplasmic growth of Bdellovibrio bacteriovorus 109J on Escherichia coli some 30 to 60% of the initial E. coli RNA-ribose disappeared as cell-associated orcinol-positive material. The levels of RNA-ribose in the suspending buffer after growth together with the RNA-ribose used for bdellovibrio DNA synthesis accounted for 50% or less of the missing RNA-ribose. With intraperiplasmic growth in the presence of added U-14C-labeled CMP, GMP, or UMP, radioactivity was found both in the respired CO2 and incorporated into the bdellovibrio cell components. The addition of exogenous unlabeled ribonucleotides markedly reduced the amounts of both the 14CO2 and 14C incorporated into the progeny bdellovibrios. During intraperiplasmic growth of B. bacteriovorus on [U-14C]ribose-labeled E. coli BJ565, ca. 74% and ca. 19% of the initial 14C was incorporated into the progeny bdellovibrios and respired CO2, respectively. Under similar growth conditions, the addition of glutamate substantially reduced only the 14CO2; however, added ribonucleotides reduced both the 14CO2 and the 14C incorporated into the progeny bdellovibrios. No similar effects were found with added ribose-5-phosphate. The distribution of 14C in the major cell components was similar in progeny bdellovibrios whether obtained from growth on [U-14C]ribose-labeled E. coli BJ565 or from E. coli plus added U-14C-labeled ribonucleotides. After intraperiplasmic growth of B. bacteriovorus on [5,6-3H-]uracil-[U-14C]ribose-labeled E. coli BJ565 (normal or heat treated), the whole-cell 14C/3H ratio of the progeny bdellovibrios was some 50% greater and reflected the higher 14C/3H ratios found in the cell fractions. B. bacteriovorus and E. coli cell extracts both contained 5'-nucleotidase, uridine phosphorylase, purine phosphorylase, deoxyribose-5-phosphate aldolase, transketolase, thymidine phosphorylase, phosphodeoxyribomutase, and transaldolase enzyme activities. The latter three enzyme activities were either absent or very low in cell extracts prepared from heat-treated E. coli cells. It is concluded that during intraperiplasmic growth B. bacteriovorus degrades some 20 to 40% of the ribonucleotides derived from the initial E. coli RNA into the base and ribose-1-phosphate moieties. The ribose-1-phosphate is further metabolized by B. bacteriovorus both for energy production and for biosynthesis, of non-nucleic acid cell material. In addition, the data indicate that during intraperiplasmic growth B. bacteriovorus can metabolize ribose only if this compound is available to it as the ribonucleoside monophosphate.

Aldolase-catalysed inactivation of glyceraldehyde-3-phosphate dehydrogenase.

ALDOLASE is known to catalyse its own inactivation in the presence of substrate and electron acceptors1. The underlying mechanism is that in the presence of electron acceptors aldolase catalyses the oxidation of dihydroxyacetone phosphate to hydroxypyruvaldehyde phosphate2,3 and this highly reactive nascent α-dicarbonyl reacts in situ with an active-centre residue4. Inactivation of aldolase is entirely due to reaction in situ of nascent hydroxypyruvaldehyde phosphate, for hydration and dilution of released hydroxypyruvaldehyde phosphate practically abolishes its contribution to inactivation4. As the inactivating agent loses reactivity on diffusion into solvent4, its action is restricted to the enzyme molecule that has produced it; other molecules of aldolase or other enzymes (transaldolase, transketolase) are not inactivated by aldolase-generated reagent1. We report here that oxidative cycles of aldolase cause the inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPD), suggesting a direct transfer of the inactivating agent between the two enzymes. Kinetic evidence for an interaction between aldolase and GAPD has been presented5.

736 ASSOCIATION OF MYOSITIS, HYPERLIPIDEMIA AND IMMUNO-REGULATORY DYSFUNCTION

Lipoprotein complexes have been associated with depressed immunologic functions. An 18-month old male presented with a history of intermittent and recurrent fevers, hepatosplenomegaly, anemia and thrombocytopenia. The patient developed a progressive polymyositis associated with elevations in CPK and aldolase enzymes; muscle biopsy revealed infiltration and replacement of striated muscles with connective tissue and mononuclear cells. Analysis of serum demonstrated a hyperlipidemia consistent with a Type I phenotype. Although the patient demonstrated only minimal depression of serum Ig levels, the addition of his serum to cultures of healthy donor peripheral blood lymphocytes (PBL) stimulated with pokeweed mitogen resulted in significant suppression of Ig synthesis and secretion. This suppressor activity was also demonstrated when washed patient PBL were cocultured with normal donor cells in the absence of patient serum. Furthermore, suppressor activity correlated with increased levels of T cells bearing surface receptors for the Fc portion of IgG (Tγ cells). These results support a model which includes the role of lipoproteins in the modulation of the immune response. (Supported in part by NIH grants CA-08748, CA-17404 and CA-19267 and American Cancer Society grant IM-126.)

Methods of predicting pale, soft, exudative pork and their application in breeding programmes—A review

The condition of pale, soft, exudative (PSE) pork has long been considered to be mainly a post mortem phenomenon. There is now substantial evidence that such pigs are suffering from a kind of myopathy, which predisposes them to an abnormal post mortem metabolism. Genetic studies on PSE muscle indicate a moderate heritability for various post mortem muscle quality traits. Reliable methods for determining the abnormal condition in the live animal would make it possible to select more effectively and economically against stress and PSE-susceptibility. Three possible methods are: (1) Analysis of blood serum for CPK, aldolase, GOT or other enzyme activities with and without preceding exercise; and for blood groups. (2) Muscle biopsy analysis for glucose-6-phosphate, lactate or energy-rich phosphates. (3) Non-destructive testing of young pigs for sensitivity to the Malignant Hyperthermia Syndrome by allowing them to inhale the anaesthetic halothane (fluothane) for a 5 min period. The development of muscular rigidity and stiffness indicates a susceptibility to stress and a potential for PSE meat. The relationships of the various methods to ultimate muscle and carcass quality, as well as the problems inherent to each method, are discussed. It is concluded that the third test seems to be the most promising for application in the breeding of pigs for optimal stress resistance and muscle quality.

Enzyme activities in different cell compartments of the involuting rat myometrium.

Marker enzymes for various intracellular fractions were measured in rat uterus myometrium during the post‐partum involution. Following a lag phase of 48 h after delivery, the activities of the cytoplasmic enzymes aldolase, glucose‐6‐phosphate dehydrogenase and creatine kinase, decreased at equal rates. The plasma membrane marker 5′‐nucleotidase, again after a lag phase of 48 h, showed a decrease in activity which was parallel to that of the cytoplasmic enzymes when allowance was made for the geometry of the cell.The mitochondrial glutamate dehydrogenase and succinate dehydrogenase activities decreased in parallel together after a lag phase of 72 h. The significantly longer lag phase of the mitochondrial enzymes can be explained in terms of the importance of the mitochondria as a source of the energy which is necessary for intracellular protein degradation.The activity of the lysosomal acid phosphatase showed no significant decrease until the involution of the tissue was essentially complete.The activities of cytosol, mitochondria and plasma membrane enzymes all fell during involution to levels below those measured in non‐pregnant control animals. This can be explained by the absence of estrogenic stimulation of the uterus during the post‐partum period, which results from suppression of ovarian function by lactation.

Aldolase-like imine formation in the mechanism of action of phosphonoacetaldehyde hydrolase

Phosphonoacetaldehyde hydrolase (EC 3.11.1.1), the bacterial enzyme that catalyses the reaction HCO-CH2-PO(OH)2+H2O leads to HCO-CH3+Pi, is inactivated by borohydride if either phosphonoacetaldehyde or acetaldehyde is present. This supports the suggestion that the substrate forms an imine with an amino group of the enzyme. Such imine formation would labilize the C-P bond in the same way that aldolase and related enzymes labilize C-C and C-H bonds (Scheme 1a).

Effects of Vitamin B6 Deficiency on Liver, Kidney, and Adipose Tissue Enzymes Associated with Carbohydrate and Lipid Metabolism, and on Glucose Uptake by Rat Epididymal Adipose Tissue

Adipose tissue and liver from vitamin B6-deficient rats have an increased lipogenic capacity. Whether this phenomenon is accompanied by changes in the activities of certain enzymes involved in the metabolism of carbohydrate and lipid, or by altered transport of glucose into adipocytes, has been studied. Five glycolytic enzymes (hexokinase, phosphoglucose isomerase, phosphofructokinase, aldolase, and pyruvate kinase), two pentose phosphate pathway enzymes (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase), malic enzyme, and ATP citrate lyase were measured in the epididymal adipose tissue, livers and kidneys of vitamin B6-deficient and control rats. Vitamin B6 deficiency did not significantly affect the glycolytic enzyme levels in the tissues studied, or the dehydrogenases measured in adipose tissue and kidneys. Liver glucose-6-phosphate dehydrogenase, and adipose tissue and liver malic enzyme were significantly lowered in deficient rats compared to ad libitum and pair-fed controls. Adipose tissue and liver ATP citrate lyase activities were also significantly decreased by vitamin B6 deficiency. In the presence of insulin, the uptake of glucose and 3-O-methyl glucose, a non-metabolizable sugar, by fat pads from deficient rats was greater than uptake by fat pads from control rats. These observations suggest that the increased glucose utilization by adipose tissue and liver of vitamin B6-deficient rats is not directly related to changes in the enzymes studied, but in the case of adipose tissue, may be explained, at least in part, by enhanced glucose uptake.