Effect of phosphorus deficiency on acid phosphatase and phytase activities in common bean (Phaseolus vulgaris L.) under symbiotic nitrogen fixation

Changes in growth, symbiotic nitrogen fixation (SNF), acid phosphatase (ACP), and phytase activities to phosphorus availability (15 and 60 μmol KH₂PO₄ plant⁻¹ week⁻¹) were compared in two recombinant lines (115 and 147) of common bean. Plant growth, nodulation and SNF were genotype and P level-dependent. 147 was more affected by P shortage (15 μmol P) than 115. Four ACP types were revealed in the nodules of both lines, ACP1 exhibiting a higher specific activity under P shortage as compared to the 60 μmol P treatment, especially in 115. A single phytase was revealed for the nodules of both lines and was significantly enhanced by P deficiency. Three ACP types were found in roots and leaves, showing increasing activity under P deficiency, especially in 115. Regardless of P supply, leaf ACP specific activity was higher than that of nodules and roots in the both lines. Interestingly, phosphorus use efficiency for N₂ fixation significantly correlated to nodule ACP activity under P shortage in the both lines. The relatively better performance of 115 as compared to 147 under P deficiency could be partly ascribed to the ability of 115 to maintain higher ACP activity. This enzyme might be involved in the remobilization of the plant Pi and its utilization for SNF.     

Purification and biochemical characterization of lysosomal acid phosphatases (EC 3.1.3.2) from blood stream forms, Trypanosoma brucei brucei

Three Acid phosphatases (ACP) were isolated and characterized from the lysosomes of blood stream forms of Trypanosoma brucei by a combination of isopynic and differential centrifugation through Ficoll, organic solvent precipitation, ion exchange on DEAE cellulose 52 and size exclusion chromatography on Sephadex G-75 columns. The purified ACP emerged as three distinct peaks (ACP I, ACP II and ACP III) with high specific activities and they moved homogenously on 12% SDS-PAGE each as a single band with relative molecular weight of 36 kDa, 25 kDa and 45 kDa respectively. The purified enzymes were active at an optimum pH and temperature of 5.5 and 40 °C respectively. The enzyme activities appeared to be ACP because their activities were enhanced at low pH values and inhibited by the acid phosphatase inhibitor, sodium fluoride. ACP I and ACP II were sensitive to l-tartrate while ACP III was insensitive to l tartrate. The kinetic analysis of the purified enzyme (ACP I, ACP II and ACP III) determined using para-nitrophenylphosphate as substrate gave K_M values of 0.2 mM, 0.15 mM and 0.5 mM. Monofunctional group sulfhydryl group inhibitors; HgCl₂, and AgCl₂ strongly inhibited the activity of ACP III and millimolar concentrations of dithiothreitol and iodoacetamide activated and inhibited the activity of the ACP III respectively, suggesting the involvement of thiol groups at the active site of the enzyme. Thus, differentiating it from ACP I and ACP II. The implication of these findings in relation to the pathology of trypanosomosis is discussed.     

Lipid biosynthesis in developing and germinating soybean cotyledons: The formation of oleate by a soluble stearyl acyl carrier protein desaturase

Extracts of developing soybean cotyledons contain a highly specific stearyl acyl carrier protein (ACP) desaturase which in the presence of NADPH, O₂, ferredoxin and ferredoxin: NADP⁺ reductase, rapidly converts stearyl ACP to oleyl ACP. The enzyme system has a high affinity for O₂, near-maximal activity being obtained at only 10 μm O₂. The pH optimum for the desaturase is 6.0. Stearic acid and stearyl-CoA, alone or in the presence of acyl carrier protein, are totally inactive. Although the enzyme is found in extracts prepared from developing soybean seeds (15–50 days after flowering), activity was not detected in extracts of germinated seeds.     

Mulberry juice freeze-dried powder attenuates the disease severity by the maintaining of colon mucosa in mice with DSS-induced acute colitis

This study aimed to evaluate the microbial compositions and gene expression related to inflammation in dextran sodium sulfate (DSS)-induced acute colitis and the effect of mulberry supplementation. Male BALB/c mice received a diet supplemented with mulberry juice freeze-dried powder (MFP) or not for 3 weeks. After 3 weeks, the mice received water containing 5% (w/v) DSS or not for 1 week. The disease activity index score in mice fed MFP was significantly decreased. A significant decrease in Bifidobacterium spp. and the Clostridium perfringens subgroup was observed in mice not fed MFP. The number of goblet cell and NLRP6 expression were observed in mice fed a diet supplemented with MFP compared with mice not fed MFP. These results may indicate that mulberry mitigates DSS-induced acute colitis by a changing the gut microbial flora and by improving mucosal conditions.     

Nature of the Fatty Acid Synthetase Systems in Parenchymal and Epidermal Cells of Allium porrum L. Leaves

Fatty acid synthesis was compared in cell-free extracts of epidermis and parenchyma of Allium porrum L. leaves. Parenchyma extracts had the major fatty acid synthetase (FAS) activity (70-90%) of the whole leaf; palmitic acid was also the major fatty acid synthesized when acetyl-coenzyme A (CoA) was the primer, but when acetyl-acyl carrier protein (ACP) was employed, C_18:0 and C_16:0 were synthesized in equal proportion. With the epidermal FAS system when either acetyl-CoA or acetyl-ACP was tested in the presence of labeled malonyl-CoA, palmitic acid was the only product synthesized. Specific activities of the FAS enzyme activities were determined in both tissue extracts.

The properties of malonyl-CoA:ACP transacylase were examined from the two different tissues. The molecular weights estimated by Sephadex G-200 chromatography were 38,000 for the epidermal enzyme and 45,000 for parenchymal enzyme. The optimal pH was for both enzymes 7.8 to 8.0 and the maximal velocity 0.4 to 0.5 micromoles per milligram protein per minute. These enzymes had different affinities for malonyl-CoA and ACP. For the malonyl-CoA:ACP transacylase of epidermis, the K_m values were 5.6 and 13.7 micromolar for malonyl-CoA and ACP, respectively, and 4.2 and 21.7 micromolar for the parenchymal enzyme. These results suggest that the FAS system in both tissues are nonassociated, that the malonyl-CoA:ACP transacylases are isozymes, and that both in epidermis and in parenchyma tissue two independent FAS system occur. Evidence would suggest that β-ketoacyl-ACP synthase II is present in the parenchymal cells but missing in the epidermal cell.

     

THE EFFECTS OF PHOSPHITE ON PHOSPHATE STARVATION RESPONSES OF ULVA LACTUCA (ULVALES,CHLOROPHYTA)1

Effects of phosphite (Phi) on phosphate (Pi) starvation responses were determined in Ulva lactuca L. by incubation in Pi‐limited (1 μM NaH₂PO₄) or Pi‐sufficient (100 μM NaH₂PO₄) seawater containing 0–3 mM Phi. Exposure to 1 μM NaH₂PO₄ decreased the growth rate and the content of free Pi and esterified‐P but increased the activities of extracellular alkaline phosphatase (EC 3.1.2.1) and intracellular acid phosphatase (ACP; EC 3.1.2.2); two ACP isozymes observed by activity staining on isoelectric focussing (IEF) gel were induced. The K_m value of Pi uptake rate was decreased by incubation with 1 μM NaH₂PO₄ and the decrease in K_m value was inhibited by 2 mM Phi, reflecting the operation of a high‐affinity Pi uptake system at low Pi concentrations. In the presence of Phi, the growth rate of Pi‐sufficient and Pi‐starved thalli decreased as Phi concentrations were increased from 0 to 2 mM. As Phi concentrations were increased from 0 to 2 mM, the free Pi contents in both Pi‐sufficient and Pi‐starved thalli decreased, but the esterified‐P contents in Pi‐starved thalli increased, whereas those in Pi‐sufficient thalli increased at 1 mM Phi and decreased at 2 mM Phi. Cell wall localized AP activity in both Pi‐sufficient and Pi‐starved thalli decreased as Phi concentrations were increased from 0 to 2 mM. Intracellular ACP activity in Pi‐starved thalli decreased as Phi concentrations were increased from 0 to 2 mM but was not affected in Pi‐sufficient thalli. The induction of ACP isozyme activity and high‐affinity Pi uptake system in Pi‐starved thalli was inhibited by Phi. The present investigation shows that Phi interrupts the sensing mechanisms of U. lactuca to Pi‐limiting conditions.     

Effect of fluorine containing compounds on the activity of glycolytic enzymes in rat hepatocytes

Inhibition of three glycolytic enzymes by NaF and Na₂PO₃F¹ in isolated rat hepatocytes has been demonstrated. The data indicate that incubation of hepatocytes with NaF or MFP and subsequent removal of NaF and MFP results in a significant inhibition of enolase (E.C. 4.2.1.11), phosphoglucomutase (E.C. 2.7.5.1.), and pyruvate kinase (E.C. 2.7.1.40). It is suggested that the fluorine compound enters the hepatocyte, becomes bound to the enzyme (phosphoglucomutase and enolase) and inhibits its activity. The inhibition of pyruvate kinase may be due to a cAMP dependent phosphorylation of the enzyme.     

Effects of NaCI stress on nitrogen and phosphorous metabolism in a true mangrove Bruguiera parviflora grown under hydroponic culture

The influence of varying levels of salinity (0, 100, 200 and 400 mM) on the activities of nitrate reductase (NR, E.C. 1.6.6.1), acid phosphatase (ACP, E.C. 3.1.3.2), and alkaline phosphatase (ALP, EC 3.1. 3.1) as well as on nitrate and phosphate uptake and total nitrogen levels in leaves of a true mangrove Bruguiera parviflora was investigated under hydroponic culture conditions. NR activity increased in 100 mM NaCl treated plants, whereas it decreased gradually in 200 and 400 mM treated plants, relative to the controls. Decreased activity of NR by NaCl stress was also accompanied by a decrease in total nitrogen level and nitrate uptake. Decreases in NR activity, nitrate (NO₃⁻), and total nitrogen level due to high salinity may be responsible for a decrease in growth and biomass production in this plant. However, salinity caused an increase in both ACP and ALP activity. Activity staining of ACP by native polyacrylamide gel electrophoresis revealed three isoforms: ACP-1, ACP-2, and ACP-3. We observed a preferential enhancement in the ACP-3 isoform by salinity. In order to understand whether the salinity-induced increase in phosphatase activity was due to inhibition in phosphate uptake, we monitored phosphate (Pi) levels in leaves and noted that phosphate levels decreased significantly under salinity. These results suggest that the induction of acid and ALP under salt stress may be due to a phosphorous deficiency.     

Immunochemical characterization of human red cell acid phosphatase isozymes

An immunological study was performed on human red cell acid phosphatase (ACP1) isozymes encoded by different alleles, each of which is expressed as an electrophoretically fast (f) isozyme and a slow (s) isozyme. These isozymes reacted as two immunochemically different groups. Allele-specific reactions were not detected between either the f isozymes or the s isozymes. Quantitation of ACP1 isozymes in red cells by crossed immunoelectrophoresis revealed a phenotype-dependent variation in the concentration of isozyme protein. A simple gene dosage effect was indicated and the ordering of the ACP1 alleles (ACP1*A < ACP1*B < ACP1*C < ACP1*E) was identical to that found for enzyme activity levels. Also, an allele effect on the proportion between s and f isozymes (s/f) was observed; the ordering here was ACP1* B < ACP1*A < ACP1*, which is the same as that reported for the susceptibility to modulation with purines. These variations in isozyme protein levels appear to account for the phenotypic differences in the intensity of the isozyme bands, when activity-stained after electrophoresis, and in the red cell enzyme activity levels. Investigation of two carriers of a Null allele showed no evidence of an aberrant protein product, and half-normal concentrations of enzyme protein were observed in the red cells of these individuals.     

Insecticidal activities of essential oil of Callistemon viminalis applied as fumigant and powder against two bruchids

The fumigant and contact toxicity of essential oil (EO) extracted from the leaves of Callistemon viminalis and its aromatized clay powder (ACP) was evaluated against adults of Acanthoscelides obtectus and Callosobruchus maculatus (Coleoptera: Bruchidae). The results obtained for fumigation assays showed that C. maculatus seems to be more susceptible (LC₅₀ = 0.019 μl/cm³) to the vapours of the essential oil than A. obtectus (LC₅₀ = 0.011 μl/cm³) after 12 h exposure. On the other hand, A. obtectus seems to be more susceptible (LD₅₀ = 0.133 μl/g) to the essential oil applied by contact on grains than C. maculatus (LD₅₀ = 0.170 μl/g) after 2 days exposure. The ACP was also very toxic towards the adults of A. obtectus (LD₅₀ = 0.100 μl/g) and C. maculatus (LD₅₀ = 0.098 μl/g) by contact on grains. At the doses of 0.133 μl/g and 0.266 μl/g, mortalities caused by ACP on grains were higher than those caused by the same dose of EO against the two bruchids. It is also established that both the EO and the ACP caused higher inhibition of F₁ progeny production of A. obtectus than that of C. maculatus. The loss of insecticidal activity of the two materials in the course of time has been observed; however, the toxicity of the ACP was more persistent than that of the oil in the course of time when applied on grains. These results suggest that EO from the leaves of C. viminalis can be used as fumigant agent against A. obtectus and C. maculatus. In addition, it could be advisable to use an adsorbent mineral material as carrier of this EO for the prolongation of its insecticidal activity in the course of time.     

Acetoacetyl-acyl carrier protein synthase, a potential regulator of fatty acid biosynthesis in bacteria

The first condensation reaction in the fatty acid biosynthetic pathway in Escherichia coli was rate-limiting as judged by analysis of the relative pool sizes of acyl carrier protein (ACP) thioester intermediates in vivo. Comparable concentrations of acetyl-ACP, malonyl-ACP, and nonesterified ACP were present during logarithmic growth, whereas long-chain acyl-ACP comprised a minor fraction of the total ACP pool. The antibiotic cerulenin was used to irreversibly inhibit both beta-ketoacyl-ACP synthases I and II. However, acyl-ACP formation in vivo was not blocked by this antibiotic, and short-chain (4-8-carbon) acyl-ACPs increased to 60% of the total ACP pool in cerulenin-treated cells. These data suggested that existence of a cerulenin-resistant condensing enzyme that was capable of catalyzing the initial steps in chain elongation. A unique enzymatic activity, acetoacetyl-ACP synthase, that specifically catalyzed the condensation of malonyl-ACP and acetyl-ACP was detected in E. coli cell extracts. Acetoacetyl-ACP synthase activity was not inhibited by cerulenin and was present in extracts prepared from a double mutant harboring genetic lesions in beta-ketoacyl-ACP synthases I and II (fabB20 fabF3). These data point to the condensation of malonyl-ACP and acetyl-ACP as the rate-controlling reaction in fatty acid biosynthesis and implicate acetoacetyl-ACP synthase as the pacemaker of fatty acid production in organisms and organelles that possess dissociated (Type II) fatty acid synthase systems.     

The leaf peroxisomal form (MFP IV) of multifunctional protein functioning in fatty-acid β-oxidation

We have purified for the first time from green leaves a multifunctional protein (MFP) involved in fatty acid -oxidation. The protein, designated MFP IV, was extracted from green leaves of three-week-old cucumber (Cucumis sativus L.) plants. Chromatography on cation exchanger, separation on hydroxylapatite, and fast-protein liquid chromatography on Phenylsuperose led to a more than 7000-fold purification and to the isolation of an apparently homogeneous 80-kDa monomeric protein. This protein is immunologically related to the glyoxysomal MFP II, as evidenced by immunodecoration with antiserum raised against MFP II. Comparison of molecular masses of all MFPs presently known revealed that the MFP prepared from green leaves (MFP IV) is distinct from MFP II (76.5 kDa) and MFP I (74 kDa) from dark-grown cotyledons. By including other properties in this comparison, we demonstrated that MFP IV can also be distinguished from the glyoxysomal MFP III (81 kDa) and the bacterially expressed MFP-a (80 kDa). Moreover, MFP IV is a constituent of leaf peroxisomes and contains the activities of 2-enoyl-CoA hydratase (EC 4.2.1.17),l-3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) and 3-hydroxyacyl-CoA epimerase.Abbreviation MFP multifunctional protein This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.     

The spatial distribution of acid phosphatase activity in ectomycorrhizal tissues depends on soil fertility and morphotype, and relates to host plant phosphorus uptake

Acid phosphatase (ACP) enzymes are involved in the mobilization of soil phosphorus (P) and polyphosphate accumulated in the fungal tissues of ectomycorrhizal roots, thereby influencing the amounts of P that are stored in the fungus and transferred to the host plant. This study evaluated the effects of ectomycorrhizal morphotype and soil fertility on ACP activity in the extraradical mycelium (ACP(myc)), the mantle (ACP(mantle)) and the Hartig net region (ACP(Hartig)) of ectomycorrhizal Nothofagus obliqua seedlings. ACP activity was quantified in vivo using enzyme-labelled fluorescence-97 (ELF-97) substrate, confocal laser microscopy and digital image processing routines. There was a significant effect of ectomycorrhizal morphotype on ACP(myc), ACP(mantle) and ACP(Hartig), while soil fertility had a significant effect on ACP(myc) and ACP(Hartig). The relative contribution of the mantle and the Hartig net region to the ACP activity on the ectomycorrhizal root was significantly affected by ectomycorrhizal morphotype and soil fertility. A positive correlation between ACP(Hartig) and the shoot P concentration was found, providing evidence that ACP activity at the fungus:root interface is involved in P transfer from the fungus to the host. It is concluded that the spatial distribution of ACP in ectomycorrhizas varies as a function of soil fertility and colonizing fungus.     

Phenotypic variation in the phosphotransferase activity of human red cell acid phosphatase (ACP1)

Summary Red cell acid phosphatase (ACP1) catalyses the transfer of phosphate from phosphate ester substrates to suitable acceptor alcohols such as methanol and glycerol. The rate of substrate turnover in the presence of acceptors is increased by the increment of the phosphotransferase reaction, thus allowing this activity to be measured. There is specificity with regard to acceptors: (a) polyols (e.g., glycerol) are better acceptors than the corresponding n-alcohols, and (b) polyol configuration and chain length determine acceptor activity. Ribitol was the most efficient acceptor found. Each of the three common ACP1 alleles is represented electrophoretically by two isozyme bands; the phosphotransferase activity of the anodal isozyme was found to be more than twice that of the cathodal isozyme. The extent of phosphotransferase activity is also genotype dependent. In the presence of 2M glycerol, the relative phosphotransferase efficiencies for the three homozygote types were: ACP1^*B=3.7, ACP1^*A=3.4, and ACP1^*C =2.5. This pattern of B>A>C is the same as found for the modulation of ACP1 by purines and folates.Publication no. 278 of the Forensic Science Group, School of Public Health, University of California     

Change in Levels of Acyl Carrier Proteins in Greening Plants

The levels of acyl carrier proteins (ACP) in greening spinachcotyledons and greening oat leaves were examined by immunoblottingwith antiserum raised against spinach ACP I. Two isoforms ofACP, ACP I and ACP II, were found in spinach cotyledons, asthey were in the green leaves. The level of ACP II was higherthan that of ACP I in etiolated cotyledons. The level of ACPI increased markedly with greening. In the greened cotyledons,the major isoform was ACP I as was the case in green spinachleaves. In oat leaves, two isoforms were also identified, oatACPI (about 12kDa) and ACP II (about 17kDa), which cross-reactedwith the antiserum against spinach ACP I, but which were differentfrom spinach ACPs I and II. The levels of oat ACPs I and IIwere very low in etiolated leaves. The increase in levels ofboth ACPs corresponded to the change in the activity of fattyacid synthesis during illumination for 24 h. During furtherillumination for 24 h, the level of ACP II increased a littlein parallel with the change in the activity of fatty acid synthesis,whereas the level of ACP I increased somewhat more. The functionof oat ACPs I and II is discussed in connection with the formationof chloroplast. (Received March 27, 1989; Accepted September 18, 1989)     

Acylation of plant acyl carrier proteins by acyl-acyl carrier protein synthetase from Escherichia coli

The acyl-acyl carrier protein synthetase from Escherichia coli has been examined for its ability to specifically acylate acyl carrier protein (ACP) from higher plants in order to develop an assay for plant ACP, and to prepare labeled acyl-ACP of plant origin. It was found that the E. coli enzyme was able to acylate ACP from spinach, soybean, avocado, corn, and several other plants. The acylation was very specific because, in crude extracts of spinach leaves where ACP represented approximately 0.1% of the total soluble protein, ACP was shown to be the only protein acylated. In contrast to other E. coli enzymes that display 2- to 10-fold lower rates with plant versus bacterial ACP, the kinetic constants (K_m and V_max) for acyl-ACP synthetase were found to be essentially identical for spinach and E. coli ACP when acylated with palmitic acid. Palmitic, myristic, lauric, stearic, and oleic acid could all be esterified to both spinach and E. coli ACP with similar specificity. Procedures are described that allow the assay of ACP in plant extracts at the nanogram level.     

Arbuscular mycorrhizal fungi and organic fertilizer influence photosynthesis,root phosphatase activity,nutrition, and growth of <Emphasis Type="Italic">Ipomoea carnea</Emphasis> ssp. <Emphasis Type="Italic">fistulosa</Emphasis>

The effect of arbuscular mycorrhizal fungi (AMF) inoculation and organic slow release fertilizer (OSRF) on photosynthesis, root phosphatase activity, nutrient acquisition, and growth of Ipomoea carnea N. von Jacquin ssp. fistulosa (K. Von Martinus ex J. Choisy) D. Austin (bush morning glory) was determined in a greenhouse study. The AMF treatments consisted of a commercial isolate of Glomus intraradices and a non-colonized (NonAMF) control. The OSRF was applied at 10, 30, and 100 % of the manufacturer’s recommended rate. AMF plants had a higher net photosynthetic rate (P _N), higher leaf elemental N, P, and K, and generally greater growth than NonAMF plants. Total colonization levels of AMF plants ranged from 27 % (100 % OSRF) to 79 % (30 % OSRF). Root acid phosphatase (ACP) and alkaline phosphatase (ALP) activities were generally higher in AMF than non-AMF plants. When compared to NonAMF at 100 % OSRF, AMF plants at 30 % OSRF had higher or comparable ACP and ALP activity, higher leaf elemental P, N, Fe, Cu, and Zn, and a greater P _N (at the end of the experiment), leading to generally greater growth parameters with the lower fertility in AMF plants. We suggest that AMF increased nutrient acquisition from an organic fertilizer source by enhancing ACP and ALP activity thus facilitating P acquisition, increasing photosynthesis, and improving plant growth.     

亚热带区4种林地土壤微生物生物量碳氮磷及酶活性特征

在位于亚热带丘陵区的长沙县大山冲林场选取地域毗邻、环境条件(立地、土壤、气候)基本一致的杉木人工林(CL)和3种次生林:马尾松-柯(又名石栎)针阔混交林(PM-LG)、南酸枣落叶阔叶林(CA)、柯-青冈常绿阔叶林(LG-CG),每种林地随机设置5个20 m×20 m的样地,分别采集表层(0—15 cm)和亚表层(15—30 cm)土壤样品,测定土壤微生物生物量碳(B_C)、氮(B_N)、磷(B_P)和蔗糖酶(INV)、脲酶(URE)、酸性磷酸酶(ACP)、过氧化氢酶(CAT)活性,分析4种林地土壤微生物生物量和酶活性及其与土壤化学性质的关系。结果表明:表层和亚表层土壤B_C、B_N、B_P和ACP活性依次为:CA LG-CG PM-LG CL,INV和URE活性依次为:LG-CG CA PM-LG CL,CAT活性依次为:CA PM-LG LG-CG CL,说明森林植被恢复对土壤微生物生物量和酶活性有明显的促进作用。通径分析表明,土壤B_C、B_N、B_P的直接影响因素和主要影响因素分别为SOC和TN/TP,TN和TN/TP,TP和SOC/TP,而TN/TP与B_C之间,TN与B_N之间具有较强的负相关;INV、ACP活性的直接影响因素主要是TN、TN/TP,其中TN/TP与INV、ACP活性具有较强的负相关;URE、CAT活性分别为B_P/TP和B_P,B_C/SOC和SOC,其中B_P与URE活性具有较强的负相关,B_C/SOC、SOC两者与CAT活性具有较强的正相关。此外,土壤B_C、B_N、B_P以及INV、URE、ACP、CAT活性的剩余余项通径系数较低,说明土壤化学性质对土壤微生物生物量,以及土壤化学性质和微生物生物量对土壤酶活性具有较大的影响。土壤B_C、B_N、B_P之间及其与土壤酶活性呈显著正相关。     

Acid phosphatase, adenosine deaminase and esterase D polymorphisms in the Spanish Basque population.

The 3 red-cell polymorphic systems acid phosphatase (ACP), adenosine deaminase (ADA) and esterase D (ESD) have been studied in a random sample of 1,112 individuals from the Basque country: The allelic frequencies obtained were ACP*A = 0.275, ACP*B = 0.718 and ACP*C = 0.007; ADA*2 = 0.021, and, ESD*2 = 0.066. The allelic frequencies have been compared with those of other Basque and other European populations. In comparison with Basques, significant differences were detected only for ACP, whereas as regards other Europeans significant differences were obtained with practically all the populations compared for the 3 genetic systems studied. The low values of the less frequent alleles, especially that for the ACP*C allele which is the lowest reported in Europe, are noteworthy.