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XYLT2 or Xylosyltransferase 2 is an enzyme which is expressed in ubiquitous and is part of the glycosyltransfe-rases family. XYLT2 promotes proteoglycans formation by attaching GAG chains to the substrate protein via transfer of xylose molecule from the donor (nucleoside diphosphate) to the protein’s serine residues. XYLT2 is present in the ER and the cis part of the Golgi, furthermore the protein is released to the extracellular matrix.

Glutathione synthetase (GSS) is the second enzyme in the glutathione biosynthesis pathway. GSS catalyses the condensation of gamma-glutamylcysteine and glycine to form glutathione. Defects in the GSS are the cause of glutathione synthetase deficiency aka GSS deficiency or 5-oxoprolinuria or pyroglutamic aciduria, which is a severe form characterized by an increased rate of hemolysis and defective function of the central nervous system.

Adenine DNA glycosylase (mutY) is an adenine DNA glycosylase active on DNA substrates including A/G, A/8-oxoG, or A/C mismatches and also has a weak guanine glycosylase activity on G/8- oxoG-containing DNA. mutY is essential for the prevention of mutations resulting from oxidative DNA impairment. Rising levels of mutY in A549 cells exposed to oxygen and infrared radiation leads to improvements in cell survival. mutY is common in neurons where mitochondrial genomes exposed to reactive oxygen species that damage DNA must uphold integrity over the whole mammalian life span.

ENO3 is one of three enolase isoenzymes in mammals. The homodimer ENO3 is located in skeletal muscle cells of adults and has a part in converting phosphoglyceric acid to phosphenolpyruvic acid in the glycolytic pathway. Mutations in ENO3 gene is linked to metabolic myopathies which is caused by low stability of the enzyme.

MGLL is a membrane-associated member of the serine hydrolase superfamily. MGLL is expressed in abundance in skeletal muscle and adipose tissue. MGLL functions jointly with hormone-sensitive lipase (LIPE) to hydrolyze intracellular triglyceride stores in adipocytes and other cells to fatty acids and glycerol. MGLL may also complement lipoprotein lipase (LPL) in completing hydrolysis of monoglycerides resulting from degradation of lipoprotein triglycerides.

UDP-Glucose Pyrophosphorylase 2, also known as UGP2 is an essential intermediary in mammalian carbohydrate inter conversions. UGP2 transfers a glucose moiety from glucose-1-phosphate to MgUTP and forms UDP-glucose and MgPPi. UDP-glucose is a direct precursor of glycogen in the liver and muscle tissue, moreover in lactating mammary gland it is converted to UDP-galactose which is next converted to lactose.

PGAM1 is part of the phosphoglycerate mutase family. PGAM1 is an essential component of glucose and 2,3-BPGA (2,3-bisphosphoglycerate) metabolism and catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM1 is a dimeric enzyme containing, in different tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM1 mutations lead to muscle phosphoglycerate mutase deficiency, a.k.a. glycogen storage disease X.

Hydroxymethylglutaryl-CoA lyase (HMGCL) is a mitochondrial matrix protein which is a member of the HMG-CoA lyase family. HMGCL is a homodimer and participates in leucine catabolism and ketogenesis, the hepatic synthesis of ketone bodies which, during fasting, provides a major source of energy for the heart, brain and kidney. More precisely, HMGCL catalyzes the final step of these processes, the cleavage of 3-hydroxy-3-methylglutaryl-CoA to acetoacetic acid and acetyl-CoA.

Core 1 Beta3-Gal-T1 also known as,C1GALT1 creates the common core 1 O-glycan structure, Gal-beta-1-3GalNAc-R, by the transfer of Gal from UDP-Gal to GalNAc-alpha-1-R. Core 1 is a precursor for lots of extended mucin-type O-glycans on cell surface and secreted glycoproteins. Studies in mice have shown that this gene takes a main role in angiogenesis, thrombopoiesis and kidney homeostasis.

Glucose-6-phosphate isomerase (GPI) is a part of the GPI family whose members encode multifunctional phosphoglucose isomerase proteins involved in energy pathways. GPI is a dimeric enzyme which catalyzes the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. Mammalian GPI also functions as a tumor-secreted cytokine and an angiogenic factor (AMF) which stimulates endothelial cell motility. In addition, GPI is a neurotrophic factor (Neuroleukin) for spinal and sensory neurons. GPI performs in different capacities inside and outside the cell. In the cytoplasm, GPI is involved in glycolysis and gluconeogenesis, while outside the cell it acts as a neurotrophic factor for spinal and sensory neurons.
Defects in the GPI gene cause the nonspherocytic hemolytic anemia and a severe enzyme deficiency can be linked to hydrops fetalis, immediate neonatal death and neurological impairment.

Uracil DNA glycosylase (UDG), or uracil-DNA glycosylase 1, is a crucial enzyme found in all life forms, involved in repairing damaged DNA by specifically removing uracil bases that are misincorporated into DNA during replication or deaminated cytosine. In various organisms, UDG goes by different names, such as b2580, JW2564, EC 3.2.2.27, DGU, UNG15, HIGM5, EC 3.2.2, HIGM4, and UNG2. Here, we delve into the E. coli UDG, examining its structure, function, and applications in molecular biology.

Structure: The crystal structure of E. coli UDG has been extensively studied, revealing that it belongs to the uracil DNA glycosylase (UDG) superfamily. The E. coli UDG monomer has 229 amino acids with a molecular weight of 25 kDa. The protein has a beta-sheet-rich structure with an alpha-helix on one side and a groove on the other side that binds to DNA. The active site of E. coli UDG contains a conserved glutamic acid residue that acts as a catalytic base to facilitate the hydrolysis of the N-glycosidic bond between uracil and the sugar phosphate backbone.

Function: E. coli UDG plays a critical role in maintaining the integrity of the genome by preventing the accumulation of mutations that can arise from the incorporation of uracil into DNA. Uracil in DNA can occur spontaneously from the deamination of cytosine or can be incorporated during DNA synthesis when dUTP is used instead of dTTP. Unrepaired uracil bases can lead to DNA damage and genomic instability, possibly resulting in cell death or disease. E. coli UDG specifically recognizes and removes uracil bases from DNA, creating an abasic site that is further processed by other repair enzymes.

Lysozymeis an antimicrobial enzyme produced by animals that are part of the innate immune system. Lysozyme is a glycoside hydrolase that catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan, which is the major component of gram-positive bacterial cell wall.Lysozymes have primarily a bacteriolytic function - those in tissues and body fluids are associated with the monocyte-macrophage system and enhance the activity of immunoagents.

HEXA is the alpha subunit of the lysosomal enzyme beta-hexosaminidase which, combined with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules having N-acetyl hexosamines terminus. The two subunits composing Beta-hexosaminidase, alpha and beta, belong to the glycosyl hydrolases family and are encoded by distinct genes. Alpha subunit gene mutations can cause Tay-Sachs disease (GM2-gangliosidosis type I).

Thymine-DNA glycosylase (TDG) is a member of the TDG/mug DNA glycosylase family.
TDG is a nuclear protein that fixes G/T mismatches to G/C pairs by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of the DNA and the mispaired thymin. In addition, TDG removes uracil and 5-bromouracil from mispairings with guanine. The TDG enzyme has an essential role in cellular defense against genetic mutation triggered by the spontaneous deamination of 5-methylcytosine and cytosine.

Phosphoglycerate mutase 2 (PGAM2) is a member of the phosphoglycerate mutase family. PGAM is a dimeric enzyme which contains in separate tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM (Phosphoglycerate mutase) catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM2 gene mutations cause muscle phosphoglycerate mutase efficiency, otherwise known as glycogen storage disease X.

Urate oxidase catalyzes the enzymatic oxidation (degrades) of uric acid into allantoin, an inactive and soluble metabolite, which is 5 to 10 fold more soluble than uric acid . Urate oxidase is an enzyme of the purine breakdown pathway that catalyses the oxidation of uric acid to allantoin. Uricase is present in numerous diverse organisms, but not in higher primates including human. Hyperuricaemia is most commonly associated with gout and also occurs in mammalians with malignancy, especially those with lymphoid malignancies due to rapid cell turnover and an increased rate of purine metabolism. Uricase is effective in the prevention and treatment of hyperuricaemia in mammalians with malignancy and in those who have undergone transplantation. It appears to act rapidly, safely and induces a more dramatic decrease in plasma levels of uric acid.

Glucuronidase Beta (GUSB) is a lysosomal hydrolase which is taking part in the stepwise degradation of glucuronic acid-containing glycosaminoglycans and plays a significant role in the degradation of dermatan and keratin sulfates. GUSB is comprised of heparin sulfate, chondroitin sulfate and hyaluronan.

GPI or Glucose-6-phosphate isomerase, is a protein, part of the multifunctional phosphoglucose isomerase family, which its members take part in energy pathways. GPI is a dimeric enzyme that enhances the isomerization of glucose-6-phosphate and fructose-6- phosphate (both reversible). In mammals, GPI acts as an angiogenic factor & tumor-secreted cytokine. The enzyme also acts as a neurotrophic factor for spinal & sensory neurons.

DCXR catalyzes the NADPH-dependent reduction of numerous pentoses, tetroses, trioses, alpha-dicarbonyl molecules and L-xylulose. DCXR takes part in the uronate cycle of glucose metabolism. DCXR participates in the water absorption and cellular osmoregulation in the proximal renal tubules by producing xylitol, an osmolyte, thus preventing osmolytic stress from occurring in the renal tubules.

DNA-3-methyladenine glycosylase (MPG) is a member of the DNA glycosylase MPG family. MPG initiates base excision repair in DNA by removing a wide variety of alkylated, deaminated, and lipid peroxidation-induced purine adducts.

Glutamyl endopeptidase (GLU-C) is an enzyme which cleaves peptide bonds on the carboxyl-terminal side of glutamic acid and, less frequently, aspartic acid (for example: Glu-|-Xaa, Asp-|-Xaa). GLU-C is a pathogenic factor involved in the adherence and colonization of human tissue. GLU-C preferentially cleaves peptide bonds on the carboxyl-terminal side of aspartate and glutamate. GLU-C is required for proteolytic maturation of thiol protease SspB and inactivation of SspC, an inhibitor of SspB. GLU-C is the most important protease for degradation of fibronectin-binding protein (FnBP) and surface protein A, which are involved in adherence to host cells. Furthermore, GLU-C protects bacteria against host defense mechanism by cleaving the immunoglobulin classes IgG, IgA and IgM. GLU-C may also be involved in the stability of secreted lipases.

GLRX2 is a multifunctional enzyme with glutathione-dependent oxidoreductase, glutathione peroxidase and glutathione S-transferase (GST) activity. The disulfide bond functions as an electron carrier in the glutathione-dependent synthesis of deoxyribonucleotides by the enzyme ribonucleotide reductase. In addition, it is also involved in reducing cytosolic protein- and non-protein-disulfides in a coupled system with glutathione reductase. Required for resistance to reactive oxygen species (ROS) by directly reducing hydroperoxides and for the detoxification of ROS-mediated damage. Glutaredoxins are a family of glutathione-dependent hydrogen donors that participate in a variety of cellular redox reactions.

UNG is a member of the Uracil-DNA glycosylase family. One of his functions is to prevent mutagenesis by eliminating uracil from DNAmolecules by cleaving the N-glycosylic bond and initiating the base-excision repair (BER) pathway. Uracil basesare formed as a result of cytosine deamination or misincorporation of dUMP residues. After a mutation is formed, the mutagenicthreat of uracil propagates through any subsequent DNA replication steps. Among the diseases associated with UNG are: congenital rubella, and immunodeficiency with hyper igm type 4.

GPD2 (Mitochondrial glycerol-3-phosphate dehydrogenase) is a Ca2+-sensitive, FAD-binding protein, which is located on the outer surface of the inner mitochondrial membrane. Two isoforms have been identified for mGPD: Isoform 1 is comprised of 727 a.a. residues, while isoform 2 lacks 126 a.a. residues of the N-terminus. GPD2 catalyses the oxidation of glycerol-3-phosphate to DHAP (dihydroxyacetone phosphate) with associated reduction of the enzyme-bound FAD. GPD2 is a testis-specific promoter of mitochondrial GPDH. GPD2 along with a cytosolic NAD-linked GPD forms the glycerol phosphate shuttle that uses the interconversion of G-3-P and DHAP to transfer reducing equivalents into mitochondria, which results in the reoxidation of NADH produced during glycolysis.
GPD2 deficiency contributes to the impairment of glucose-stimulated INS discharge in a number of animal models of non-INS dependent diabetes mellitus. GPD2 up-regulation as a result of a highly glycolytic environment contributes to the general increase in ROS generation and may lead to the progression of prostate cancer.