The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Barry Wolf - One of the best experts on this subject based on the ideXlab platform.

  • biotinidase knockout mice show cellular energy deficit and altered carbon metabolism gene expression similar to that of nutritional biotin deprivation clues for the pathogenesis in the human inherited disorder
    Molecular Genetics and Metabolism, 2013
    Co-Authors: Alain De J Hernandezvazquez, Kirit Pindolia, R Hernandezgonzalez, A Herediaantunez, Isabel Ibarragonzalez, Daniel Ortegacuellar, Barry Wolf, Antonio Velazquezarellano
    Abstract:

    Abstract Biotin is the prosthetic group of carboxylases that have important roles in the metabolism of glucose, fatty acids and amino acids. Biotinidase has a key role in the reutilization of the biotin, catalyzing the hydrolysis of Biocytin (e-N-biotinyl- l -lysine) and Biocytin-containing peptides derived from carboxylase turnover, thus contributing substantially to the bioavailability of this vitamin. Deficient activity of biotinidase causes late-onset multiple carboxylase in humans, whose pathogenic mechanisms are poorly understood. Here we show that a knock-out biotinidase-deficient mouse from a C57BL/6 background that was fed a low biotin diet develops severe ATP deficit with activation of the energy sensor adenosine monophosphate (AMP)-activated protein kinase (AMPK), inhibition of the signaling protein mTOR, driver of protein synthesis and growth, and affecting the expression of central-carbon metabolism genes. In addition, sensitivity to insulin is augmented. These changes are similar to those observed in nutritionally biotin-starved rats. These findings further our understanding of the pathogenesis of human biotinidase deficiency.

  • biotinidase and its roles in biotin metabolism
    Clinica Chimica Acta, 1996
    Co-Authors: Jeanne Hymes, Barry Wolf
    Abstract:

    Biotinidase is the enzyme responsible for the recycling of the vitamin biotin. Biotinidase acts as a hydrolase by cleaving Biocytin and biotinyl-peptides, thereby liberating biotin for reutilization. Biotinidase is also important for making biotin bioavailable from bound dietary sources. The interest in this enzyme has been increased by the discovery of biotinidase deficiency, an inherited biotin-responsive disorder that can result in neurological and cutaneous abnormalities, but can be treated effectively with biotin supplementation. Biotinidase has recently been shown to be biotinylated in the presence of Biocytin, but not biotin, at neutral and alkaline pH. This raises the possibility that biotinidase acts as a biotin-binding or biotin-carrier protein. Biotinidase has also been shown to have biotinyl-transferase activity resulting in the transfer of biotin from Biocytin to nucleophilic acceptors, such as histones. Transferase activity occurs at physiological pH and at physiological concentrations of Biocytin and, therefore, may be the main function of the enzyme in serum and other tissues. These novel functions of the enzyme may indicate that biotinidase plays a critical role in the metabolism of biotin in nuclei, particularly of neuronal cells. The role of biotinidase in biotin metabolism may be a paradigm for better understanding the metabolism of other vitamins.

  • biotinylation of histones by human serum biotinidase assessment of biotinyl transferase activity in sera from normal individuals and children with biotinidase deficiency
    Biochemical and Molecular Medicine, 1995
    Co-Authors: Jeanne Hymes, Kristin Fleischhauer, Barry Wolf
    Abstract:

    Serum biotinidase has biotinyl-transferase activity in addition to Biocytin hydrolase activity. A sensitive assay for biotinyl-transferase activity was developed based on the transfer of biotin from Biocytin to histones. Biotinidase biotinyl-transferase occurs at physiological and alkaline pHs, whereas hydrolysis of Biocytin occurs optimally at pH 4.5 to 6.0. Measurement of hydrolysis requires micromolar concentrations of Biocytin, whereas biotinylation of histones can be detected readily at 1.5 nM Biocytin. Because polylysine is readily biotinylated by biotinidase in the presence of Biocytin, whereas polyarginine is not, the enzyme likely transfers biotin to the ϵ-amino group of lysyl residues. To determine if patients who are deficient in Biocytin hydrolase activity are also deficient in biotinyl-transferase activity, serum from 103 children (25 identified by exhibiting clinical symptoms and 78 detected by newborn screening) with profound biotinidase deficiency (less than 10% of mean normal biotinyl-p-aminobenzoate hydrolyzing activity) were assessed for biotinyl-transferase activity and for the presence of cross-reacting material (CRM) to antibodies prepared against purified serum biotinidase. Sera from all symptomatic: patients, both CRM-negative and CRM-positive, had no biotinyl-transferase activity. Sera that was CRM-negative from children ascertained by newborn screening also had no biotinyl-transferase activity, whereas sera from 67% of the CRM-positive children identified by newborn screening had varying degrees of biotinyl-transferase activity. These results indicate that there is a large group of enzyme-deficient children detected by newborn screening who are different biochemically from those who are symptomatic. The clinical relevance of having some degree of biotinyl-transferase activity for individuals with biotinidase deficiency remains to be determined. In addition, it is important to determine if biotinyl-transferase activity, especially biotinylation of histones, is a physiological function of biotinidase.

  • biotinylation of histones by human serum biotinidase assessment of biotinyl transferase activity in sera from normal individuals and children with biotinidase deficiency
    Biochemical and Molecular Medicine, 1995
    Co-Authors: Jeanne Hymes, K Fleischhauer, Barry Wolf
    Abstract:

    Serum biotinidase has biotinyl-transferase activity in addition to Biocytin hydrolase activity. A sensitive assay for biotinyl-transferase activity was developed based on the transfer of biotin from Biocytin to histones. Biotinidase biotinyl-transferase occurs at physiological and alkaline pHs, whereas hydrolysis of Biocytin occurs optimally at pH 4.5 to 6.0. Measurement of hydrolysis requires micromolar concentrations of Biocytin, whereas biotinylation of histones can be detected readily at 1.5 nM Biocytin. Because polylysine is readily biotinylated by biotinidase in the presence of Biocytin, whereas polyarginine is not, the enzyme likely transfers biotin to the epsilon-amino group of lysyl residues. To determine if patients who are deficient in Biocytin hydrolase activity are also deficient in biotinyl-transferase activity, serum from 103 children (25 identified by exhibiting clinical symptoms and 78 detected by newborn screening) with profound biotinidase deficiency (less than 10% of mean normal biotinyl-p-aminobenzoate hydrolyzing activity) were assessed for biotinyl-transferase activity and for the presence of cross-reacting material (CRM) to antibodies prepared against purified serum biotinidase. Sera from all symptomatic patients, both CRM-negative and CRM-positive, had no biotinyl-transferase activity. Sera that was CRM-negative from children ascertained by newborn screening also had no biotinyl-transferase activity, whereas sera from 67% of the CRM-positive children identified by newborn screening had varying degrees of biotinyl-transferase activity. These results indicate that there is a large group of enzyme-deficient children detected by newborn screening who are different biochemically from those who are symptomatic. The clinical relevance of having some degree of biotinyl-transferase activity for individuals with biotinidase deficiency remains to be determined. In addition, it is important to determine if biotinyl-transferase activity, especially biotinylation of histones, is a physiological function of biotinidase.

  • Biotinylation of biotinidase following incubation with Biocytin.
    Clinica Chimica Acta, 1995
    Co-Authors: Jeanne Hymes, Kristin Fleischhauer, Barry Wolf
    Abstract:

    Abstract Human serum biotinidase, purified to homogeneity (1920 units/mg protein), was incubated with Biocytin prior to electrophoresis and transblotting with avidin-peroxidase. Avidin reacted with biotinidase maximally when incubated at pH 7.5–9, less at pH 7 and none below pH 7. No avidin reactivity occurred when biotinidase was incubated with biotin or in the absence of Biocytin. Inclusion of the nucleophilic acceptors, ethanolamine or hydroxylamine, to the incubation mixture with Biocytin and biotinidase resulted in loss of avidin reactivity. High concentrations of mercaptoethanol also prevented avidin reactivity. These results suggest that biotinidase can be biotinylated in the presence of Biocytin at neutral to alkaline pH probably through a thioester bond formed with a cysteine residue in the active site of the enzyme. Biotinidase may then function as a biotinylating enzyme when incubated with appropriate nucleophilic acceptors.

Marina Sciancalepore - One of the best experts on this subject based on the ideXlab platform.

Jeanne Hymes - One of the best experts on this subject based on the ideXlab platform.

  • biotinidase and its roles in biotin metabolism
    Clinica Chimica Acta, 1996
    Co-Authors: Jeanne Hymes, Barry Wolf
    Abstract:

    Biotinidase is the enzyme responsible for the recycling of the vitamin biotin. Biotinidase acts as a hydrolase by cleaving Biocytin and biotinyl-peptides, thereby liberating biotin for reutilization. Biotinidase is also important for making biotin bioavailable from bound dietary sources. The interest in this enzyme has been increased by the discovery of biotinidase deficiency, an inherited biotin-responsive disorder that can result in neurological and cutaneous abnormalities, but can be treated effectively with biotin supplementation. Biotinidase has recently been shown to be biotinylated in the presence of Biocytin, but not biotin, at neutral and alkaline pH. This raises the possibility that biotinidase acts as a biotin-binding or biotin-carrier protein. Biotinidase has also been shown to have biotinyl-transferase activity resulting in the transfer of biotin from Biocytin to nucleophilic acceptors, such as histones. Transferase activity occurs at physiological pH and at physiological concentrations of Biocytin and, therefore, may be the main function of the enzyme in serum and other tissues. These novel functions of the enzyme may indicate that biotinidase plays a critical role in the metabolism of biotin in nuclei, particularly of neuronal cells. The role of biotinidase in biotin metabolism may be a paradigm for better understanding the metabolism of other vitamins.

  • biotinylation of histones by human serum biotinidase assessment of biotinyl transferase activity in sera from normal individuals and children with biotinidase deficiency
    Biochemical and Molecular Medicine, 1995
    Co-Authors: Jeanne Hymes, Kristin Fleischhauer, Barry Wolf
    Abstract:

    Serum biotinidase has biotinyl-transferase activity in addition to Biocytin hydrolase activity. A sensitive assay for biotinyl-transferase activity was developed based on the transfer of biotin from Biocytin to histones. Biotinidase biotinyl-transferase occurs at physiological and alkaline pHs, whereas hydrolysis of Biocytin occurs optimally at pH 4.5 to 6.0. Measurement of hydrolysis requires micromolar concentrations of Biocytin, whereas biotinylation of histones can be detected readily at 1.5 nM Biocytin. Because polylysine is readily biotinylated by biotinidase in the presence of Biocytin, whereas polyarginine is not, the enzyme likely transfers biotin to the ϵ-amino group of lysyl residues. To determine if patients who are deficient in Biocytin hydrolase activity are also deficient in biotinyl-transferase activity, serum from 103 children (25 identified by exhibiting clinical symptoms and 78 detected by newborn screening) with profound biotinidase deficiency (less than 10% of mean normal biotinyl-p-aminobenzoate hydrolyzing activity) were assessed for biotinyl-transferase activity and for the presence of cross-reacting material (CRM) to antibodies prepared against purified serum biotinidase. Sera from all symptomatic: patients, both CRM-negative and CRM-positive, had no biotinyl-transferase activity. Sera that was CRM-negative from children ascertained by newborn screening also had no biotinyl-transferase activity, whereas sera from 67% of the CRM-positive children identified by newborn screening had varying degrees of biotinyl-transferase activity. These results indicate that there is a large group of enzyme-deficient children detected by newborn screening who are different biochemically from those who are symptomatic. The clinical relevance of having some degree of biotinyl-transferase activity for individuals with biotinidase deficiency remains to be determined. In addition, it is important to determine if biotinyl-transferase activity, especially biotinylation of histones, is a physiological function of biotinidase.

  • biotinylation of histones by human serum biotinidase assessment of biotinyl transferase activity in sera from normal individuals and children with biotinidase deficiency
    Biochemical and Molecular Medicine, 1995
    Co-Authors: Jeanne Hymes, K Fleischhauer, Barry Wolf
    Abstract:

    Serum biotinidase has biotinyl-transferase activity in addition to Biocytin hydrolase activity. A sensitive assay for biotinyl-transferase activity was developed based on the transfer of biotin from Biocytin to histones. Biotinidase biotinyl-transferase occurs at physiological and alkaline pHs, whereas hydrolysis of Biocytin occurs optimally at pH 4.5 to 6.0. Measurement of hydrolysis requires micromolar concentrations of Biocytin, whereas biotinylation of histones can be detected readily at 1.5 nM Biocytin. Because polylysine is readily biotinylated by biotinidase in the presence of Biocytin, whereas polyarginine is not, the enzyme likely transfers biotin to the epsilon-amino group of lysyl residues. To determine if patients who are deficient in Biocytin hydrolase activity are also deficient in biotinyl-transferase activity, serum from 103 children (25 identified by exhibiting clinical symptoms and 78 detected by newborn screening) with profound biotinidase deficiency (less than 10% of mean normal biotinyl-p-aminobenzoate hydrolyzing activity) were assessed for biotinyl-transferase activity and for the presence of cross-reacting material (CRM) to antibodies prepared against purified serum biotinidase. Sera from all symptomatic patients, both CRM-negative and CRM-positive, had no biotinyl-transferase activity. Sera that was CRM-negative from children ascertained by newborn screening also had no biotinyl-transferase activity, whereas sera from 67% of the CRM-positive children identified by newborn screening had varying degrees of biotinyl-transferase activity. These results indicate that there is a large group of enzyme-deficient children detected by newborn screening who are different biochemically from those who are symptomatic. The clinical relevance of having some degree of biotinyl-transferase activity for individuals with biotinidase deficiency remains to be determined. In addition, it is important to determine if biotinyl-transferase activity, especially biotinylation of histones, is a physiological function of biotinidase.

  • Biotinylation of biotinidase following incubation with Biocytin.
    Clinica Chimica Acta, 1995
    Co-Authors: Jeanne Hymes, Kristin Fleischhauer, Barry Wolf
    Abstract:

    Abstract Human serum biotinidase, purified to homogeneity (1920 units/mg protein), was incubated with Biocytin prior to electrophoresis and transblotting with avidin-peroxidase. Avidin reacted with biotinidase maximally when incubated at pH 7.5–9, less at pH 7 and none below pH 7. No avidin reactivity occurred when biotinidase was incubated with biotin or in the absence of Biocytin. Inclusion of the nucleophilic acceptors, ethanolamine or hydroxylamine, to the incubation mixture with Biocytin and biotinidase resulted in loss of avidin reactivity. High concentrations of mercaptoethanol also prevented avidin reactivity. These results suggest that biotinidase can be biotinylated in the presence of Biocytin at neutral to alkaline pH probably through a thioester bond formed with a cysteine residue in the active site of the enzyme. Biotinidase may then function as a biotinylating enzyme when incubated with appropriate nucleophilic acceptors.

Benjamin Schatzman - One of the best experts on this subject based on the ideXlab platform.

  • transport of the biotin dietary derivative Biocytin n biotinyl l lysine in rat small intestine
    Gastroenterology, 1993
    Co-Authors: Hamid M Said, Le Phuc Thuy, Larry Sweetman, Benjamin Schatzman
    Abstract:

    Abstract Background: Biocytin is an important end product of intraluminal digestion of dietary protein-bound biotin. Limited studies are available regarding the ability of the small intestine to transport Biocytin and about the mechanism involved. The aim of the present study was to delineate these issues. Methods: Transport of [ 3 H]-Biocytin was examined using everted sacs from rat intestine. Results: Mucosal-to-serosal transport of low (0.022 μmol/L) and high (5 μmol/L) concentrations of Biocytin were linear for up to 20 minutes of incubation. Transport of Biocytin as a function of concentration (0.022–5 μmol/L) was linear ( r = 0.99) and occurred at a rate of 22,062 fmol · g tissue (wet wt) −1 · 15 min −1 . Addition of high concentrations of unlabeled Biocytin, biotin, biotin methyl ester, and lysine did not cause a significant inhibition of the transport of [ 3 H]-Biocytin. Furthermore, transport of Biocytin was independent of Na + concentration, pH, energy, and temperature. Compared with transport of equimolar concentrations of free biotin, transport of Biocytin (0.022 μmol/L) was significantly lower in both the jejunum and the ileum. Conclusions: (1) Biocytin transport in rat intestine is lower than that of free biotin and occurs via simple physical diffusion. (2) In the rat, efficient absorption and optimal bioavailability of dietary protein-bound biotin necessitates its conversion to free biotin.

Natasa Savic - One of the best experts on this subject based on the ideXlab platform.