Evidence that GABAA Receptor Subunit mRNA Expression During Development Is Regulated by GABAA Receptor Stimulation

Abstract: The expression of six mRNA species (α2, α3, α5, β2, β3, and γ2) encoding for GABA_A receptor subunits was followed in cultured early postnatal cortical neurons by in situ hybridization histochemistry. In untreated control cultures it was found that these subunit mRNA expression profiles closely follow those seen during development in vivo. α3, α5, and β3 subunit expression declined, α2 expression increased, whereas β2 and γ2 subunit mRNA expression remained relatively constant. To test the hypothesis that GABA_A receptor stimulation regulates these expression profiles, we tested the effect of a GABA_A receptor positive modulator, allopregnanolone, and a GABA_A receptor noncompetitive antagonist, tert -butylbicyclophosphorothionate (TBPS). It was found that allopregnanolone augmented the rate at which the α3, α5, or β3 subunit mRNA expression declined and prevented the increase in α2 subunit mRNA expression. As well, allopregnanolone down-regulated β2 subunit mRNA expression. TBPS, on the other hand, up-regulated α3, α5, β2, and β3 subunit mRNA expression. It also down-regulated the expression of α2 subunit mRNA. Both allopregnanolone and TBPS had no effect on γ2 subunit mRNA expression. These results imply that the developmental switchover of GABA receptor subunit mRNA expression is regulated by GABA_A receptor activity.     

Variation of DNA Polymerase Activities in Chick Neural Retina as a Function of Age

The activities of DNA polymerases α, β, and γ and of thymidine kinase were determined in the chick neural retina at different stages of embryonic development (starting at seven days) and after hatching (up to five years). Crude extracts of neural retinae were fractionated by centrifugation on sucrose gradients and the enzymatic activities measured using specific assays. The DNA polymerase a activity decreases greatly between 7 and 11 days of incubation. This decrease parallels the decline in mitotic activity. However, a constant residual activity remains after hatching, even in the oldest animals. DNA polymerase β activity increases slightly between 7 and 14 days of incubation; it then decreases slowly until seven days after hatching and remains constant thereafter. DNA polymerase γ activity is maximal between 7 and 14 days of incubation and then decreases until hatching. The activity of thymidine kinase increases slightly during the embryonic life until hatching and remains almost constant thereafter. The implication of these enzymes in DNA replication and repair processes is discussed.     

Steroidogenesis in the Ovarian Follicle of Medaka (Oryzias latipes, a daily spawner) during Oocyte Maturation

The metabolism of ¹⁴C-labeled steroid precursors by cell-free homogenates of medaka ( Oryzias latipes , a daily spawner) ovarian follicles at 12 different developmental stages was examined using thin layer chromatography (TLC). The radioactive metabolites produced were identified and tested for their ability to induce germinal vesicle breakdown (GVBD) in oocytes in an in vitro homologous bioassay. When homogenates of follicles isolated during oocyte maturation were incubated with ¹⁴C-labeled 17α-hydroxyprogesterone, 13 metabolites were detected in TLC. Among these metabolites, one metabolite exhibited very high maturation inducing activity by the in vitro bioassay. This metabolite was identified as 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP) by its chromatographic mobility in TLC and recrystallization to constant specific activity. 17α,20β-DP production was high in follicles collected between 10 and 6 hr before spawning. A much less biologically active metabolite, 17α,20β-dihydroxy-5β-pregnane-3-one appeared in follicles immediately after the formation of 17α,20β-DP. A similar pattern of steroidogenesis was observed when the follicles were incubated with ¹⁴C-labeled pregnenolone and progesterone. The timely synthesis of 17α,20β-DP in medaka at the onset of oocyte maturation, together with the demonstration that this progestogen is the most potent inducer of oocyte maturation in vitro , provides further evidence that 17α,20β-DP is the naturally occurring maturation-inducing hormone in the medaka. The results also suggest that the conversion of 17α,20β-DP to its 5β-reduced metabolite may be an inactivation process.     

Temperature-dependent changes in Photosystem II heterogeneity of attached leaves under high light

Attached leaves of pumpkin ( Cucurbita pepo L. cv. Jattiläismeloni) were exposed to high light intensity at room temperature (ca 23°C) and at 1°C. Fluorescence parameters and electron transport activities measured from isolated thylakoids indicated faster photoinhibition of PSII at low temperature. Separation of the α and β components of the complementary area above the fluorescence induction curve of dichlorophenyl-dimethylurea-poisoned thylakoids revealed that at low temperature only the α-centers declined during exposure to high light intensity while the content of functional β-centers remained constant. Freeze-fracture electron microscopy showed no decrease in the density of particles on the appressed exoplasmic fracture face, indicating that the photoinhibited α-centers remained in the appressed membranes at 1°C. Because of the function of the repair and protective mechanisms of PSII, strong light induced less photoinhibition at room temperature, but more complicated changes occurred in the α/β-heterogeneity of PSII. During the first 30 min at high light intensity the decrease in α-centers was almost as large as at 1°C, but in contrast to the situation at low temperature the decrease in α-centers was compensated for by a significant increase in PSIIβ-centers. Changes in the density and size of freeze-fracture particles suggest that this increase in β-centers was due to migration of phosphorylated light-harvesting complex from appressed to non-appressed thylakoid membranes while the PSII core remained in the appressed membranes. This situation, however, was only transient and was followed by a rapid decrease in the functionalβ-centers.     

Isolation and analysis of a gene encoding α-glucuronidase, an enzyme with a novel primary structure involved in the breakdown of xylan

This is the first report describing the analysis of a gene encoding an α-glucuronidase, an enzyme essential for the complete breakdown of substituted xylans. A DNA fragment that carries the gene for α-glucuronidase was isolated from chromosomal DNA of the hyperthermophilic bacterium Thermotoga maritima MSB8. The α-glucuronidase gene ( aguA ) was identified and characterized with the aid of nucleotide sequence analysis, deletion experiments and expression studies in Escherichia coli , and the start of the coding region was defined by amino-terminal sequencing of the purified recombinant enzyme. The aguA gene encodes a 674-amino-acid, largely hydrophilic polypeptide with a calculated molecular mass of 78 593 Da. The α-glucuronidase of T. maritima has a novel primary structure with no significant similarity to any other known amino acid sequence. The recombinant enzyme was purified to homogeneity as judged by SDS–PAGE. Gel filtration analysis at low salt concentrations revealed a high apparent molecular mass (<630kDa) for the recombinant enzyme, but the oligomeric structure changed upon variation of the ionic strength or the pH, yielding hexameric and/or dimeric forms which were also enzymatically active. The enzyme hydrolysed 2- O -(4- O -methyl-α- d -glucopyranosyluronic acid)- d -xylobiose (MeGlcAX₂) to xylobiose and 4- O -methylglucuronic acid. The K _m for MeGlcAX₂ was 0.95mM. The pH optimum was 6.3. Maximum activity was measured at 85°C, about 25°C or more above the values reported for all other α-glucuronidases known to date. When incubated at 55–75°C, the enzyme suffered partial inactivation, but thereafter the residual activity remained nearly constant for several days.     

Partial purification of cell wall α-galactosidases and α-arabinosidases from Cicer arietinum epicotyls. Relationship with cell wall autolytic processes

Two protein fractions with activity as α-galactosidase (EC 3.2.1.22) and α-arabinosidase (EC 3.2.1.55), respectively, were identified in the proteins of cell wall of Cicer arietinum L. cv. Castellana extracted with 3 M LiCl. These fractions were partially purified by gel filtration chromatography (Bio Gel P-150), increasing the specific arabinosidase activity 57-fold and the α-galactosidase activity 6-fold. Other protein fractions with glucosidase (EC 3.2.1.21) and glucanase (EC 3.2.1.6) activity also appeared. According to earlier authors, α-arabinosidases and α-galactosidases are related to alterations in linkages occurring in cell walls, since the enzymes are able to hydrolyze isolated wall polymers. However, our preparations hydrolyze intact cell walls only to a very limited extent, such that their participation in the autolytic processes of cell walls can be ruled out.     

Extracellular α-glucosidase of an alkalophilic microorganism, Bacillus sp. ATCC 21591

Abstract Bacillus sp. ATCC 21591, an alkalophilic bacterium, produces 3 enzymes associated with degradation of starch-α-amylase, pullulanase and α-glucosidase. The latter reached a maximum after 24 h growth. Highest activities of α-glucosidase and pullulanase were obtained when the initial pH of the medium was 9.7 and although at pH 10.4 highest biomass was attained after 48 h no α-glucosidase was present. The pH optimum for activity with maltose as substrate was 7.0, which is surprisingly low for an alkalophilic organism. The enzyme was substrate specific for p -nitrophenyl- α -D-glucoside, maltose and maltotriose in that order. Forty eight times the activity was located in the cell-free supernatant, relative to that found intracellulary. Transferase activity was detected - the major end-product formed from maltose was a compound with an R _f -value similar to isomaltose.     

α-galactosidase from the yeast Candida javanica

Summary α-Galactosidase (Ec 3.2.1.22) was obtained from the yeast C. javanica grown on a mineral culture medium supplemented with melibiose plus raffinose. The cell-bound α-galactosidase and the preparations from the culture filtrate and from the cells exhibited maximum activity at pH 4 and 70°C. After 15 min at 70°C, 70% of the α-galactosidase activity was recovered, and after 15 min at 80°C complete inactivation was observed. The Michaelis constant (Km) of α-galactosidase on pNPG and on melibiose was about 11 mM. Galactose as a reaction product had no effect on α-galactosidase activity of the preparation from the cells, whereas glucose (2 and 10 mM) increased the activity. On the basis of polyacrylamide gel electrophoresis, the preparation from the cell extract, obtained after ultrafiltration and ethanol precipitation, showed only an active band which stained with Coomassie-blue but not with Schiff-periodate. The α-galactosidase from C. javanica is α-galactosidase A, it lacks invertase and it reduces group B specificity of erythrocytes.     

A novel splicing variant encoding putative catalytic α subunit of maize protein kinase CK2

A cDNA highly homologous to the known catalytic α subunit of protein kinase CK2 was cloned from maize ( Zea mays ). It was designated ZmCK 2α-4 (accession no. AAF76187). Sequence analysis shows that ZmCK2α-4 and the previously identified ZmCK2α-1 (accession no. X61387) are transcribed from the same gene, ZmPKCK2AL (accession no. Y11649), but at different levels in various maize organs and at different stages of development. The cDNA encoding ZmCK2α-4 has three potential translation initiation sites. The three putative variants of ZmCK2α-4 were expressed in Escherichia coli as GST-fusion proteins and purified from bacterial extracts. In contrast to the previously characterized ZmCK2αs, the obtained GST:ZmCK2α-4 proteins were catalytically inactive as monomers or in the presence of equimolar amounts of the human CK2β. However, GST:ZmCK2α-4 did phosphorylate casein in the presence of a large excess of the β subunit. The activity of ZmCK2α-4 toward casein could also be stimulated by increasing ATP concentration. Modeling studies have shown that there is no interaction between the N-terminal segment of ZmCK2α-4 and the activation loop responsible for constitutive catalytic activity of CK2α. Preliminary results suggest that ZmCK2α-4 may function as a negative regulator of other CK2s, and at certain circumstances as a holoenzyme which catalytic activity is stimulated by specific regulatory subunit(s).     

Adrenergic Control of Rat Pineal NO Synthase

Abstract: We have previously shown that exposure of rats to constant light (LL) induced a decrease in NO synthase (NOS) activity in the pineal gland. We present here the evidence that chronic (5 days) norepinephrine (NE) or isoproterenol treatment prevents the effect of LL and enhances pineal NOS activity in LL animals. This effect of NE appears to be mediated by β-adrenoceptors, because it was not mimicked by the α-agonist phenylephrine. Pineal NOS activity was reduced in 16-h light/8-h dark animals treated for 4 days with the β-adrenergic antagonist propranolol but not with the α₁-antagonist prazosin, indicating again an involvement of β-adrenergic receptor in the control of NOS. Treatment with adrenergic antagonists did not affect cortical NOS activity, suggesting that the control of NOS is different in these two tissues or that the pineal expresses a specific isoform of the enzyme. Taken together, these data suggest that NE controls NOS in the pineal gland through β-adrenergic receptors. To our knowledge, this represent the first demonstration of a regulation of NOS by a neurotransmitter in the CNS, as assayed under V _max conditions.     

Different Modulation of Protein Kinase C Isozymes in Dibutyryl Cyclic AMP-Differentiated PC12h Cells

Abstract: PC12h cells can be differentiated into sympathetic neuron-like cells by various agents, including nerve growth factor, basic fibroblast growth factor, cyclic AMP analogues, and protein kinase C (PKC) activators. To study the involvement of PKC in the process of PC12h cell differentiation by cyclic AMP treatment, PKC isozymes (α, βI, βII, and γ) were analyzed using column chromatography and immunoblotting. Two PKC isozymes, PKC(α) and PKC(βII), were predominantly detected in PC12h cells. When stimulated by dibutyryl cyclic AMP, PKC(α) levels declined in the cytosolic fraction of the cells, whereas PKC(βII) levels increased. Increased PKC(βII) levels were also detected in the particulate fraction, whereas particulate PKC(α) levels did not change. The total PKC activity decreased in the cytosolic fraction following cyclic AMP stimulation of PC12h cells, whereas it stayed constant in the particulate fraction. Fractionation on a hydroxyapatite column showed a decreased level of PKC(α) activity and a transient increase followed by a decreased level of PKC(βII) activity. This discrepancy between increased PKC(βII) immunoreactivity and reduced PKC(βII) activity suggested the presence of nonactivatable PKC(βII) in cyclic AMP-treated PC12h extract. These findings indicate that PKC(α) and PKC(βII) are differentially regulated during the differentiation of PC12h cells. In addition, the differentiation of PC12h cells triggered by cyclic AMP seems to involve characteristic alterations of PKC isozymes.     

Effect of tunicamycin on α-galactosidase secretion by Aspergillus nidulans and the importance of N-glycosylation

Abstract Aspergillus nidulans released α-galactosidase into the culture medium during the exponential growth on either lactose or galactose as the only carbon source. This enzyme is a glycoprotein. Its treatment with endoglycosidases produces a reduction in its molecular mass but the resulting enzyme conserved some of their carbohydrate components in addition to its enzymatic activity. Mycelia of A. nidulans growing in the presence of tunicamycin synthesized an underglycosylated α-galactosidase which was not released into the culture media but remained bound to the cell-wall. Tunicamycin did not prevent the synthesis and secretion of α-galactosidase by protoplasts. N-linked oligosaccharide chains seem not to be essential for the synthesis and secretion of α-galactosidase of A. nidulans , but they could be necessary for proper targeting at the extracellular level.     

Tyrosine 39 of GH13 <Emphasis Type="Italic">α</Emphasis>-amylase from <Emphasis Type="Italic">Thermococcus hydrothermalis</Emphasis> contributes to its thermostability

The presented work is focused on the naturally thermostable α-amylase from the archaebacterium Thermococcus hydrothermalis. From the evolutionary point of view, the archaeal α-amylases are most closely related to plant α-amylases. In a wider sense, especially when the evolutionary trees are based on the less conserved part of their amino acid sequences (e.g. domain C succeeding the catalytic TIM-barrel), also the representatives of bacterial liquefying (Bacillus licheniformis) and saccharifying (Bacillus subtilis) α-amylases as well as the one from Thermotoga maritima should be included into the relatedness with the archaeal and plant α-amylases. Based on the bioinformatics analysis of the α-amylase from T. hydrothermalis, the position of tyrosine 39 (Y16 if the putative 23-residue long signal peptide is considered) was mutated to isoleucine (present in the α-amylase from T. maritima) by the in vitro mutagenesis. The biochemical characterization of the wild-type α-amylase and its Y39I mutant revealed that: (i) the specific activity of both enzymes was approximately equivalent (0.55 ± 0.13 U/mg for the wild-type and 0.52 ± 0.15 U/mg for the Y39I); (ii) the mutant exhibited decreased temperature optimum (from 85°C for the wild-type to 80°C for the Y39I); and (iii) the pH optimum remained the same (pH 5.5 for both enzymes). The remaining activity of the α-amylases was also tested by one-hour incubation at 80°C, 85°C, 90°C and 100°C. Since the wild-type α-amylase lost only 13% of its activity after one-hour incubation at the highest tested temperature (100°C), whereas 27% decrease was seen for the mutant Y39I under the same conditions, it is possible to conclude that the position of tyrosine 39 could contribute to the thermostability of the α-amylase from T. hydrothermalis.     

Na,K-ATPase expression in C2C12 cells during myogenesis: Minimal contribution of α2 Isoform to Na,K transport

Summary Cells of the murine skeletal muscle line, C₂C₁₂, undergo differentiation from mononuclear myoblasts to multinuclear myotubes that express a number of proteins associated with striated muscle. We examined the relationship between the abundance of the mRNAs encoding the fast-twitch Ca-ATPase and the α isoforms of Na,K-ATPase and the subsequent expression of their respective polypeptides. Both the mRNA and protein levels of the αl isoform remained constant throughout differentiation. In contrast, the content of mRNAs encoding the α2 isoform and fasttwitch Ca-ATPase increased coordinately with the abundance of their corresponding polypeptides during myotube development. Despite the dramatic increase in α2 expression, estimates of in vitro Na,K-ATPase activity and assessments of in vivo transport activity suggest that α2 contributes little to ionic homeostasis in C₂C₁₂ myotubes.     

Cryptic fragment alpha4 LG4-5 derived from laminin alpha4 chain inhibits de novo adipogenesis by modulating the effect of fibroblast growth factor-2

Cleavage of the extracellular matrix (ECM) by proteolysis unmasks cryptic sites and generates novel fragments with biological activities functionally distinct from those of the intact ECM molecule. The laminin G-like (LG)4-5 fragment has been shown to be excised from the laminin α 4 chain in various tissues. However, the functional role of this fragment has remained unknown to date. To investigate this, we prepared α 4 LG1-3 and α 4 LG4-5 fragments by elastase digestion of recombinant α 4 LG1-5, and examined their effects on de novo adipogenesis in mice at the site of injection of basement membrane extract (Matrigel) and fibroblast growth factor (FGF)-2. Although the addition of whole α 4 LG1-5 suppressed adipogenesis to some extent, the α 4 LG4-5 fragment could strongly suppress adipogenesis at a concentration of less than 20 n m . Addition of the α 4 LG4 module, which contains a heparin-binding region, had a suppressive effect, but this was lost in mutants with reduced heparin-binding activity. In addition, antibodies against the extracellular domain of syndecan-2 and -4, which are known receptors for the α 4 LG4 module, suppressed adipogenesis. Thus, these results suggest that the cryptic α 4 LG4-5 fragment derived from the laminin α 4 chain inhibits de novo adipogenesis by modulating the effect of FGF-2 through syndecans.     

Lithium Modulation of Phosphoinositide Signaling System in Rat Cortex: Selective Effect on Phorbol Ester Binding

Abstract— Recent work indicates that the therapeutic action of lithium may be mediated through perturbation of postreceptor second messenger systems. To elucidate further the postreceptor cellular sites of action(s) of lithium, the effect of chronic lithium treatment on various components of the receptor-activated phosphoinositide pathway was investigated. We found that chronic administration of lithium (0.2% LiCI, 21 days) to adult male rats did not significantly affect phosphoinositide hydrolysis in cerebral cortical slices induced by carbachol (1 m M ) or NaF (10 m M ). Nor did the same treatment alter the carbachol (1 m M ) potentiation of guanosine 5'-(γ-thio)triphosphate (30 μ M ) stimulation of phosphoinositide hydrolysis (an index of receptor/G protein coupling) in cortical membranes. Immunoblotting studies revealed no changes in the levels of Gα_q/11 immunoreactivity in the cortex after chronic lithium treatment. The levels of protein kinase C, as revealed by specific binding of [³H]phorbol dibutyrate ([³H]PDBu), were significantly reduced in the cytosolic fraction and increased in the particulate fraction of rat cortex after chronic lithium, whereas the K _D of [³H]PDBu binding remained relatively constant. A small and insignificant decrease in the density of [³H]inositol 1,4,5-trisphosphate binding was also found in the cortex. The above data suggest that chronic lithium treatment affects neither the muscarinic cholinergic-linked phosphoinositide turnover nor the putative G protein α subunit (Gα_q/11) responsible for phospholipase C activation. However, a possible translocation and activation of protein kinase C activity may be significant in the therapeutic effect of this mood-stabilizing agent.     

α-galactosidase from germinating guar (Cyamopsis tetragonolobus) seeds

The changes in α-galactosidase activity in guar (Cyamopsis tetragonolobus) seeds was followed during seven days of germination. The enzyme activity was maximal on the first day of germination and gradually decreased during subsequent days. On the second day of germination the partially purified enzyme upon ion-exchange chromatography on CM-Sephadex C-50 was resolved into α-galactosidase-A (anionic), α-galactosidase-C₁ (cationic) and α-galactosidase-C₂ (cationic) and their relative proportions were 28,12 and 60%, respectively. The combined α-galactosidase C₁ and C₂ activities increased in the first two days of germination followed by significant decrease after the 3rd day onwards, whereas α-galactosidase-A remained fairly constant throughout the germination period, α-Galactosidase-A and C2 had differentK _m and V_max values withp-nitrophenyl α-D-galactopyranoside, raffinose and melibiose as substrates and also differed in their thermal stabilities     

Isoform Specific Reductions in Na+,K+-ATPase Catalytic (α) Subunits in the Nerve of Rats with Streptozotocin-Induced Diabetes

Abstract: Na⁺,K⁺-ATPase activity in nerve is reduced in rats with streptozotocin-induced diabetes; three different isoforms of the α (catalytic) subunit of the enzyme are present in nerve. Using western blot to determine subunit isoform polypeptide levels in sciatic nerve, we found a substantial reduction in α1-isoform polypeptide (88% at 3 weeks, 94% at 8 weeks) after induction of diabetes by streptozotocin. Reductions in α2 and α3 polypeptide were smaller and not statistically significant. The reduction in amount of all three isoform polypeptides in the nerve of 3-week diabetic animals was corrected by administration of insulin. Accumulation of α1 polypeptide at a nerve ligature indicated that rapid transport of that polypeptide in nerve occurs with normal kinetics. The results implicate a specific marked deficit in α1, much more than α2 or α3, catalytic subunit isoform of Na⁺,K⁺-ATPase in the pathogenesis of diabetic neuropathy.     

Changes in proteolytic enzyme activities and transformation of nitrogenous compounds in the germinating seeds of kidney bean (Phaseolus vulgaris)

Summary Hydrolytic activity towards synthetic substrates and denatured proteins was measured in the extracts of the seeds of kidney bean at various stages of germination up to 16 days.Of the peptide hydrolases, chymotrypsin-type activity was stable for the first 7 days, then rapidly increased towards the end; leucine aminopeptidase activity decreased to a minimum (8th day) then slowly increased again; trypsin-type activity remained constant throughout.Proteolytic and autodigesting activities showed an optimum between pH 5.0 and 5.5. Both activities decreased slowly first, then rose to a sharp maximum at the 8th day. The haemoglobin-digesting activity after a minimum increased again at the 14th day. The autodigesting activity had an additional maximum.Concomitant with these changes, non-protein nitrogen increased twofold by the 5th day, remained constant up to the 12th day and then increased again. Protein content on the other hand decreased first, had a maximum at the 9th day after which it steadily decreased again. The amounts of albumins and globulins changed independently of each other: albumins decreased continuously with the exception of a steady period (5–9th days), while globulins were more stable except for a sharp minimum (6–7th days) and a steady decrease after the 13th day.The following abbreviations were used: BAPA, -N-benzoyl-L-arginine-p-nitroanilidine; N-CBZ-Tyr-PA, -N-carbobenzoxy-L-tyrosine-p-nitrophenyl ester; LPA, leucyl-p.nitroanilidine; BAEE, -N-benzoyl-L-arginine ethyl ester, TCA, trichloroacetic acid.     

Enolase Activity and Isoenzyme Distribution in Human Brain Regions and Tumors

Abstract: The distribution of enolase (EC 4.2.1.11) activity and isoenzymes in various regions of human brain at different ages (from 23 weeks of gestation to 95 years) and in brain tumors has been determined. Total enolase activity increased in all regions with age. No significant differences were found in the relative proportions of αα-, αγ-, and γγ-enolase isoenzymes in the various brain regions, determined by agarose gel electrophoresis. Type αα-enolase was the predominant isoenzyme, and αγ-enolase represented a substantial proportion of the total enolase activity. Astrocytomas, anaplastic astrocytomas, glioblastomas, and meningiomas possessed lower enolase activity than normal brain. Among astrocytic tumors, total enolase activity correlated with malignancy. Astrocytomas possessed the lowest and glioblastomas the highest enolase activity. All tumors possessed a higher proportion of αα-enolase and a lower proportion of γγ-enolase than the normal human brain. Among astrocytic tumors, glioblastomas were the tumors with the highest proportion of αα-enolase and lowest proportion of γγ-enolase.