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PubMed1983

Distribution of pyruvate kinase type L and M2 in microdissected periportal and perivenous rat liver tissue with different dietary states.

Pyruvate kinase type L and M2 activities were measured in microdissected periportal and perivenous liver tissue from rats in different dietary states. A specific antibody against pyruvate kinase type L was used to distinguish the two isoenzymes. Using separated cells it was found that the L-isoenzyme was essentially restricted to the parenchymal and the M2-isoenzyme to the non-parenchymal cells. Pyruvate kinase type L activity in the perivenous zone was about twice as high as in the periportal zone in both male and female fed rats. Starvation for 48 h led to a decrease of the overall activity and to a lower perivenous-periportal gradient. After refeeding for 48 h the overall activity and the gradient were increased to above the normal level. Pyruvate kinase type M2 was homogenously distributed within the liver acinus. After 48 h starvation no change in the overall activity nor in the zonal distribution was observed. Refed rats exhibited a slightly reduced overall activity. Since the hepatocytes contain the total regulatory L- but no M2-pyruvate kinase the heterogeneous distribution of the L-isoenzyme under different dietary states supports the model of metabolic zonation of liver parenchyma with glycolysis predominantly in the perivenous zone.

Animals↗
PubMed1993

Divergent binding sites in pyruvate kinases I and II from Escherichia coli.

Pyridoxal 5'-phosphate incorporation into pyruvate kinase II from E. coli was decreased by the substrate phosphoenolpyruvate and increased by the allosteric activator ribose 5-phosphate, the total incorporation being linearly related to inactivation. Four lysyl residues were substantially modified, whatever the incubation conditions were while two additional residues became reactive only in the presence of the allosteric activator. Six tryptic peptides containing modified lysines were purified and sequenced. They defined five regions of pyruvate kinase II, since one of them contained two labelled lysines and included a peptide which also appeared independently. Sequence comparison with E. coli type I, yeast and cat muscle pyruvate kinases shows that the binding regions of pyruvate kinase II are clearly divergent from those of pyruvate kinase I and of the eukaryotic enzymes.

Allosteric Regulation↗
PubMed2005

Glucose, lactate, and pyruvate concentrations in dogs with babesiosis.

OBJECTIVE: To document changes in glucose, lactate, and pyruvate concentrations in dogs with severe or complicated babesiosis; assess relationships among glucose, lactate, and pyruvate concentrations in those dogs; and compare clinical and laboratory variables in dogs with and without hypoglycemia and hyperlactatemia. ANIMALS: 20 dogs with naturally developing severe or complicated babesiosis. PROCEDURE: Samples and measurements were obtained before treatment was initiated. Babesiosis was diagnosed by examination of blood smears. Arterial blood pressure measurement, parasite quantification, CBC count, serum biochemical analysis, urinalysis, venous blood gas analysis, and acid-base determination were performed. Glucose, lactate, and pyruvate concentrations were measured in samples of venous blood. RESULTS: We detected a significant negative correlation between glucose and lactate concentrations. Glucose, lactate, and pyruvate concentrations all differed significantly between dogs that died and those that survived. Three of 5 dogs that died had concurrent hypoglycemia, hyperlactatemia, and hyperpyruvatemia. Hypoglycemic dogs differed significantly from normoglycemic dogs with regard to lactate, urea, and bicarbonate concentrations; lactate-to-pyruvate ratio; percentage parasitemia; and PCO2. Dogs with hyperlactatemia differed significantly from normolactatemic dogs with regard to clinical collapse; alanine transaminase activity; concentrations of bilirubin, urea, creatinine, and bicarbonate; percentage parasitemia; and PCO2. CONCLUSIONS AND CLINICAL RELEVANCE: Abnormal carbohydrate metabolism is commonly evident in dogs with severe or complicated babesiosis and is often associated with changes in other clinical and laboratory variables. Significant differences were found between survivors and nonsurvivors. Hypoglycemia should be assessed and aggressively treated in dogs with babesiosis. Lactate concentration can be used as an indicator of disease severity.

Acid-Base Equilibrium↗
PubMed1985

Myocardial pyruvate, lactate, and orthophosphate contents under different postischemic conditions. A study in a paracorporeal rat heart model.

The myocardial contents of pyruvate, lactate and orthophosphate after ischemia were investigated in a paracorporeal rat heart model under different conditions. The arterial blood was supplemented with phosphoenolpyruvate (PEP) and adenosine triphosphate early during reperfusion of excised hearts subjected to 15 min of complete global ischemia at 37 degrees C. The increase in myocardial pyruvate was significant after 4 min of reperfusion compared with the content in non-supplemented hearts subjected to the same ischemic trauma. Such dynamic changes were not observed for lactate and orthophosphate under corresponding conditions. The distinct increase in myocardial pyruvate content on supplementation with PEP and adenosine triphosphate was most probably due to an adenosine triphosphate-mediated PEP translocation into myocardial cells, with rapid metabolization of translocated PEP into adenosine triphosphate (in the presence of cellular adenosine diphosphate) and pyruvate. The pyruvate and lactate relationship varied, depending on the postischemic conditions. The postischemic myocardial orthophosphate content was stable, with only minor fluctuations. This possibility to supply the postischemic myocardium with substrate for immediate intracellular energy production is of clinical interest and merits further studies.

Adenosine Triphosphate↗
PubMed1975

Effects of insulin upon fatty acids synthesis from pyruvate, lactate, and glucose in rat mammary cells.

In isolated rat mammary secretory cells, insulin stimulated fatty acid synthesis from pyruvate three times, stimulated glucose conversion to fatty acids 1.2 to 1.5 times, and decreased lactate conversion to fatty acids 20 to 30%. Incubation of glucose and pyruvate together depressed fatty acid synthesis from glucose not attributable to isotope dilution. Glucose stimulated conversion of pyruvate-2-14 carbon to fatty acids without significantly affecting pyruvate-1-14 carbon conversion to 14-carbon dioxide. At differing concentrations, the electron acceptors phenazine methosulfate and N,N,N',N'-tetramethyl-p-phenylene-diamine alleviated the depression by insulin of lactate conversion to fatty acids. The data support concepts that: (1) insulin acts at important sites other than or in addition to glucose transport in regulating mammary secretory cell metabolism and, particularly, fatty acid synthesis; (2) insulin actions upon fatty acid synthesis can vary dependent upon cellular redox state (insulin increases fatty acid synthesis in cells with a low redox state and decreases fatty acid synthesis in cells in a very reduced state); and (3) pyruvate depresses glucose carbon flux through the Embden-Meyerhof pathway.

Animals↗
PubMed1988

Assay of rat plasma pyruvate kinase activity with luciferin-luciferase.

An assay method for pyruvate kinase in rat plasma is described. Plasma samples were incubated with ADP and phosphoenolpyruvate in Tris buffer solution. The ATP produced by pyruvate kinase was measured by photocounting after the addition of a commercially available luciferin-luciferase preparation. Interference by ATP or adenylate kinase originally present in the sample was removed by a high degree of dilution. The assay is sensitive, reproducible, and rapid, especially when used for large numbers of samples. By this method, pyruvate kinase activity in normal rats was determined to be 0.51 +/- 0.05 (n = 6) U/ml plasma. In rats fed a vitamin E-deficient basal diet for 7, 10, or 14 weeks, pyruvate kinase activities were 0.70 +/- 0.11, 1.64 +/- 0.51, and 4.28 +/- 0.85 (n = 6) U/ml plasma, respectively. This method appears to be useful for the determination of pyruvate kinase activity in nutritional or pharmacological studies.

Animals↗
PubMed2000

Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos.

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.

Analysis of Variance↗
PubMed1975

The control of the synthesis of pyruvate carboxylase in Pseudomonas citronellolis. Evience from double labeling studies.

The level of pyruvate carboxylase in Pseudmonas citronellolis is controlled by the carbon source of the growth medium. The activity of the enzyme is highest in cells grown on lactate or glucose and virtually absent in cells grown on malate or aspartate. Double labeling studies with 3H- and 14C-labeled leucine confirm that pyruvate carboxylase is synthesized in the presence of lactate but not in the presence of aspartate. The studies also show that coordinated regulation occurs at the level of the synthesis of the two polypeptides which make up pyruvate carboxylase in P. citronellolis, rather than at the stages of their assembly into protomers or the biotinylation of the apoenzyme. There is no evidence for control of the catalytic acitivity of the holoenzyme via effectors. In all other varieties of pyruvate carboxylase examined thus far, the enzyme appears to be constitutive with regulation accomplished either through effector modulation of holoenzyme activity (pyruvate carbox-lase from animal sources, yeast, several species of bacteria) or through control of the biotinylation of the apoenzyme by holocarboxylase synthetase (Bacillus stearothermophilus, yeast).

Aspartic Acid↗
PubMed2001

Angiogenic activity of pyruvic acid in in vivo and in vitro angiogenesis models.

The excessive growth of a tumor requires high rates of glucose uptake and glycolysis and continuous recruitment of new blood vessels. Here, we provide several lines of evidence showing that pyruvic acid, the end product of glycolysis, exhibits strong angiogenic activity. Pyruvic acid promoted angiogenesis in chorioallantoic membrane assay and in vivo mouse Matrigel plug assay. Pyruvic acid also positively affects angiogenic cascade, DNA synthesis, migration, and tube formation in bovine aortic endothelial cells. Furthermore, mRNA expression of fibroblast growth factor receptor-2 and vascular endothelial growth factor was enhanced by pyruvic acid. These results strongly suggest that pyruvic acid plays an important role in angiogenesis for tumor growth and metastasis.

Allantois↗
PubMed2002

[From gene to disease; hereditary non-spherocytic hemolytic anemia caused by pyruvate kinase deficiency].

Pyruvate kinase (PK) deficiency is a common cause of hereditary non-spherocytic haemolytic anaemia. It is an autosomal recessive disorder caused by mutations in the gene coding for erythrocyte and liver-type pyruvate kinase (PKLR). So far, more than 130 mutations in this gene have been identified. Clinical symptoms, usually restricted to homozygous and compound-heterozygous individuals, are variable, ranging from neonatal jaundice requiring erythrocyte transfusions to a fully compensated haemolytic anaemia. The exact mechanism of erythrocyte destruction is unknown, however adenosine-triphosphate depletion and an increase in 2,3-disphosphoglycerate are thought to be important. The diagnosis of pyruvate kinase deficiency depends upon the demonstration of low PK enzyme activity. Due to the pitfalls in determining true PK activity, DNA testing is a valuable tool in the diagnosis of pyruvate kinase deficiency. By centralizing the molecular diagnostics of pyruvate kinase deficiency in Utrecht, more care can be provided for the diagnosis, treatment and support of patients.

Anemia, Hemolytic, Congenital Nonspherocytic↗
PubMed2003

Bcl-2 inhibits tumor necrosis factor-alpha-mediated increase of glycolytic enzyme activities and enhances pyruvate carboxylase activity.

To understand the effects of bcl-2 on glucose metabolism and tumor necrosis factor-alpha (TNF-alpha) mediated cytotoxicity, the activities of glycolytic enzymes (hexokinase, 6-phosphofructo-1-kinase, and pyruvate kinase), lactate dehydrogenase, pyruvate carboxylase, and phosphoenolpyruvate carboxykinase were examined with or without TNF-alpha treatment in TNF-alpha sensitive L929 cells and TNF-alpha resistant bcl-2 transfected L929 cells. In TNF-alpha-treated L929 cells, the activities of the glycolytic enzymes and lactate dehydrogenase greatly increased, but there was no detectable change in phosphoenolpyruvate carboxykinase. Pyruvate carboxylase activity decreased by about 25% between 6 and 12 h after TNF-alpha treatment. The activities of the glycolytic enzymes and lactate dehydrogenase in bcl-2 transfected L929 cells were lower than in L929 cells upon TNF-alpha treatment. On the other hand, the activity of pyruvate carboxylase was 20-100% greater after 6 h of TNF-alpha treatment than in the L929 cells. The activity of phosphoenolpyruvate carboxykinase of bcl-2 trasfected L929 cells was lower by up to 25% than in L929 cells after 12 h. The increase of pyruvate carboxylase activity and decrease of phosphoenolpyruvate carboxykinase activity in bcl-2 transfected L929 cells may contribute to the protective effects of bcl-2 against TNF-alpha mediated cytotoxicity.

Animals↗
PubMed2004

[Effect of pyruvate on the dependence of electromechanical activity on stimulation frequency in human myocardium].

The aim of the study was to determine the effect of pyruvate, a substrate of energetic metabolism, on the dependence of electromechanical activity on stimulation frequency in human myocardium. The experiments were performed on human ventricle myocardium from patients undergoing cardiac corrective open heart surgery at Clinic of Cardiac Surgery in Kaunas University of Medicine by using standard method of registration of myocardium electromechanical activity. The stimulation frequency of myocardial strips were 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 and 3 Hz, duration of pulses -2-5 ms. In control, i.e. at perfusion of mycoardial strips by Tyrode solution and stimulation frequency 1 Hz, an average of contraction force (P) was 0.94+/-0.18 mN (n=12), half time of relaxation (t(a)) - 178.88+/-9.31 ms (n=12), and action potential duration measured at 50% repolarization level (VP(50)) - 294.75+/-27.95 ms (n=9). Pyruvate (10 mM) increased P to 159.9+/-13.4% (p<0.00), t(a)- 106.9+/-2.2% (n=12) (p<0.001), and VP(50)- 111.1+/-7.4% (n=5) (p<0.05), as compared to control. In the absence of pyruvate values of P, t(a) and VP(50) of myocardial strips were higher at 0.2 Hz and 0.5 Hz and lower at 3 Hz compared with those at 1 Hz of stimulation frequency. Although the dependence of these parameters on stimulation frequency in the presence of pyruvate (10 mM) was not altered but their values were persistently increased at all stimulation frequencies. The present data indicate that pyruvate is an effective inotropic agent, which can improve contractility function in wide-ranging diapason of stimulation frequency in failing human heart.

Action Potentials↗
PubMed1976

Nuclear magnetic relaxation studies of the conformation of adenosine 5'-triphosphate on pyruvate kinase from rabbit muscle.

The conformation of adenosine 5'-triphosphate in the manganese complex of pyruvate kinase from rabbit muscle was determined from six metal to nucleus distances derived by nuclear magnetic relaxation techniques. On the enzyme, no direct metal-ATP coordination exists. The phosphorous atoms of ATP are 4.9 to 5.1 A away from manganese, a distance which indicates either a predominantly (greater than or equal to 94%) second sphere complex or, less likely, a highly distorted inner sphere complex. Thus, water ligands or ligands from the protein might intervene between the ATP molecule and the divalent metal ion and facilitate their interaction. The metal-gammaP distance of 5 A for pyruvate kinase-bound ATP is equal to that found for the phosphorous atom of phosphoenolpyruvate and cobalt(II) on pyruvate kinase (Melamud, E., and Mildvan, A. S. (1975) J. Biol. Chem. 250, 8193-8201), which is consistent with the overlap in space of the P-enolpyruvate-phosphorus and the gammaP of ATP at the active site. This observation explains the competitive binding of these two substrates to the enzyme, as detected by NMR and by early kinetic studies. From the phosphorus data and from measurements of the relaxation rates of 3 protons of ATP in the pyruvate kinase-metal-ATP complex, the conformation of ATP was characterized as extended with distances of 6.0, 9.1, and 7.5 A from manganese to the H8, H2, and H'1 protons, respectively. The torsion angle about the glycosidic bond (chi) which defines the conformation of the enzyme-bound riboside and adenine rings was determined to be 30 degrees. In contrast, the conformation of the binary Mn(II)-ATP complex in solution is folded around the metal with direct manganese coordination of the alpha-, beta-, and gamma-phosphorus atoms, and with metal to proton distances of 4.5, 6.4, and 6.2 A for the H8, H2, and H'1 protons, suggesting a second sphere manganese-adenine interaction. The chi angle equals 90 degrees for the binary complex primarily because of the metal-base interaction. Thus, a profound change in the conformation and structure of Mn(II)-ATP from a folded chelate to an extended second sphere complex results when the nucleotide binds to pyruvate kinase.

Adenosine Triphosphate↗
PubMed1989

Regulation of the expression of the L-type pyruvate kinase gene in adult rat hepatocytes in primary culture.

Hepatocytes isolated from adult fasted rats and cultured in the presence of thyroid hormones, glucocorticoids, and in a serum-free medium conserve the essentials of their differentiated function and hormonal sensitivity for at least 1 week. In these cells, the gene for L-type pyruvate kinase is expressed only when glucose and insulin are present together, each of them being inactive by itself. Inhibition of the expression of the L-type pyruvate kinase gene which occurs when glucose and/or insulin are removed from the culture medium is not associated with accumulation of the phosphoenolpyruvate carboxykinase mRNA, which argues against the involvement of intracellular cyclic AMP in this phenomenon. Rather, a transcriptional activator, derived from carbohydrate metabolism and accumulating in the presence of insulin, seems to be needed to support the expression of the L-type pyruvate kinase gene. Glucagon, in vitro as in vivo, inhibits production of the L-type pyruvate kinase mRNAs. In addition to their roles on the production of these mRNAs, glucose and insulin on the one hand and glucagon on the other have profound effects on the stability of the L-type pyruvate kinase messengers: the half-life of the mRNA whose production has been blocked by actinomycin D is 1 h in the presence of glucagon and 24 h in the presence of glucose and insulin. Glucagon and glucose/insulin partially antagonize each other's effect on mRNA stability.

Animals↗
PubMed1989

Rates of pyruvate utilization and lactate formation by lymphocytes from young and aged rats.

The rates of pyruvate utilization and lactate formation were measured in lymphocytes from young (newly weaned), adult (3-month old) and aged (15-month old) rats. Lymphocytes obtained from mesenteric lymph nodes were incubated at 37 degrees C for 1 h. The conversion of pyruvate to lactate accounted for 92.5% of the total pyruvate utilized by lymphocytes from young rats and was 34.2% and 44.5% for adult and aged rats, respectively. When lymphocytes were stimulated with concanavalin A there was an increase of 65.6% and 37.1% in the rates of pyruvate utilization by lymphocytes from young and adult rats, respectively. No changes in pyruvate utilization were observed in response to concanavalin A in lymphocytes from aged rats.

Aging↗
PubMed1978

Lactate and pyruvate utilization by the spermatozoa of infertile human males.

In studying the metabolic pathway of lactate and pyruvate in human spermatozoa from fertile and infertile subjects, pyruvate 1-C14 and lactate 1-C14 were used as substrates in a radiorespirometry system. Spermatozoa from patients with 20 +/- 2.0/10(6) spz/ml and decreased motility (group B) showed a more active decarboxylation of both pyruvate 1-C14 and lactate 1-C14 with a higher production of lactate C14, oxaloacetate, citrate, and isocitrate than those from fertile normal subjects (group A). Spermatozoa from fertile patients with normal counts but low motility (35 +/- 2.0% +++ motility) showed a similar rate of decarboxtlation of pyruvate 1-C14 but a greater rate of decarboxylation of lactate 1-C14 than those from fertile subjects. The low utilization of pyruvate by the spermatozoa from group C infertile patients, with intermediate counts and motility could be explained by a metabolic failure similar to that produced by some inhibitors of the respiratory chain. We do not have an explanation for the metabolic behavior observed in spermatozoa from group B patients, and further research on this point is desirable.

Adult↗
PubMed1985

AMP deaminase reaction as a control system of glycolysis in yeast. Role of ammonium ion in the interaction of phosphofructokinase and pyruvate kinase activity with the adenylate energy charge.

The role of ammonium ion and AMP deaminase (EC 3.5.4.6) reaction in the activation of phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) by the decrease in the adenylate energy charge was investigated using permeabilized yeast cells. Response of AMP deaminase, phosphofructokinase, and pyruvate kinase to variation in the energy charge is typical of the ATP-regenerating enzymes: an activation with the decrease in the energy charge under the in situ conditions. The addition of polyamine activated AMP deaminase in situ, resulting in the subsequent increase in ammonium production, which can stimulate the phosphofructokinase activity with the increase in the optimal energy charge value giving maximal activity of the enzyme. The optimal energy charge value of phosphofructokinase was 0.2-0.25 in the absence of ammonium ion and was shifted to the value above 0.5 by the addition of ammonium ion, whereas Pi, an activator of the enzyme showed little effect on the increase in the optimal energy charge value. The optimal energy charge value of AMP deaminase and pyruvate kinase was not affected by the addition of their effectors. Modulation of the response to the energy charge of phosphofructokinase and pyruvate kinase was analyzed in terms of the "activation coefficient," which was defined as the ratio of the activity at the energy charge of 0.6 to that at the value of 0.9. Activation of phosphofructokinase by the physiological decrease in the energy charge (0.9 to 0.6) can be enhanced by the increase in ammonium ion specifically, although the coefficient of pyruvate kinase remained unaffected by ammonium ion. These results suggest that the AMP deaminase reaction as an ammonium-forming reaction can participate in a key role in the stimulation of phosphofructokinase or glycolytic flux in cells.

AMP Deaminase↗
PubMed1988

Phosphorylation and inactivation of the pyruvate dehydrogenase from the anaerobic parasitic nematode, Ascaris suum. Stoichiometry and amino acid sequence around the phosphorylation sites.

Tryptic digestion of the fully phosphorylated Ascaris suum pyruvate dehydrogenase complex yielded a single tetradecapeptide containing 2 phosphorylated serine residues. Its amino acid sequence was Tyr-Ser-Gly-His-Ser(P)-Met-Ser-Asp-Pro-Gly-Thr-Ser(P)-Tyr-Arg and was very similar to one of the tryptic phosphopeptides isolated from mammalian and yeast pyruvate dehydrogenases. At partial phosphorylation, three peptides were isolated which corresponded to the monophosphorylated (sites 1 and 2) and diphosphorylated tetradecapeptides. In contrast to results reported from mammalian complexes, phosphorylation of the ascarid complex paralleled inactivation, and no additional phosphorylation occurred after inactivation was complete. Complete inactivation of the complex was associated with the incorporation of 1.7-1.9 mol of phosphoryl groups/mol of alpha-pyruvate dehydrogenase subunit, and the strict preference of the pyruvate dehydrogenase kinase for site 1 was not observed. Whereas site 1 was initially phosphorylated more rapidly than site 2, at 50% inactivation, 41% of the incorporated phosphoryl groups were incorporated into site 2. In addition, substantial amounts of peptide monophosphorylated at site 2 also accumulated, suggesting that prior phosphorylation at site 1 was not necessary for phosphorylation at site 2. Phosphorylation also caused a marked decrease in the mobility of the alpha-pyruvate dehydrogenase subunit on sodium dodecyl sulfate-polyacrylamide gels and the apparent separation of mono- and diphosphorylated forms of the enzyme. The significance of these observations in the regulation of the unique anaerobic mitochondrial metabolism of A. suum is discussed.

Amino Acid Sequence↗