関: exoglycosidase、glycosidase、glycoside hydrolase

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/31 23:09:25」(JST)

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An Endoglycosidase is an enzyme that releases oligosaccharides from glycoproteins or glycolipids. It may also cleave polysaccharide chains between residues that are not the terminal residue, although releasing oligosaccharides from conjugated protein and lipid molecules is more common.

It breaks the glycosidic bonds between two sugar monomer in the polymer. It is different from exoglycosidase that it does not do so at the terminal residue. Hence, it is used to release long carbohydrates from conjugated molecules. If an exoglycosidase were used, every monomer in the polymer would have to be removed, one by one from the chain, taking a long time. An endoglycosidase cleaves, giving a polymeric product.

PROTEIN-x₁-x₂-x₃-x₄-x₅-x₆-x₇-x₈-x₉-x₁₀-x₁₁-...-x_n

Mechanism Overview

Examples of various endoglycosidases
Endoglycosidase	Gylcoside	Bond hydrolysed^[1]
D
F	Glc-Nac	Glc // Nac
F1
F2	Glc-Nac	Glc // Nac
H	diacetylchitobiose	Nac // asparagine
Nac: N-Acetylglucosamine

The mechanism is an enzymatic hydrolysis that requires two critical molecules; a proton donor (most likely an acid) and a nucleophile(most likely a base).^[2] The Endoglycosidases mechanism has two forms; an acid catalyzed protonation of the glycosidic oxygen yielding stereochemical retention at the anomeric carbon or an acid catalyzed protonation of the glycosidic oxygen with a concomitant attack of a water molecule activated by the base residue yielding a stereochemical inversion.^[2]

Both mechanisms exhibit the same distance between the proton donor and the glycosidic oxygen, situating the proton donor close enough to the glycosidic oxygen for hydrogen bonding.^[2] It is the distance between the nucleophile and the anomeric carbon where the two mechanisms begin to diverge. Because the inversion mechanism must accommodate enough space for the water molecule, the nucleophile is situated further away from the anomeric carbon. In the retention mechanism, this distance is only 5.5 -7 angstroms but increases to 9-10 angstroms in the inversion mechanism. Furthermore, the inversion mechanism was found to proceed through a single displacement mechanism involving an oxocarbenium ion-like transition state. Due to the retention mechanism’s proximity between the two carboxyl groups, it goes through a double displacement mechanism that produces a covalent glycosyl-enzyme intermediate.^[3]^[4]

A exoglycosidase would remove each carbohydrate monomer (x) one by one from the end, starting at x_n, whereas and endogylcosidase can cut at any glycosidic bond (-) and may cleave after a signature 'link oligosaccharide' that links certain carbohydrates to certain proteins.

Applications and potential uses

There has been great potential shown in the use of endoglycosidase enzymes undergoing mutagenesis. This new mutated enzyme when exposed to the proper compounds will undergo oligosaccharide synthesis and will not hydrolyze the newly formed polymer chains.^[2]^[4] This is an extremely useful tool, as oligosaccharides have a great potential for use as therapeutics. For example, globo H hexasaccharide will indicate cancer related malignant cell transformation in the breast, prostate and ovaries.^[5]

Endoglycosidases also have potential application in fighting autoimmune diseases such as arthritis and systemic lupus erythematosus. In 2008, a team of researchers demonstrated that injection of endgoglycosidase S “efficiently removes the IgG-associated sugar domain in vivo and interferes with autoantibody-mediated proinflammatory processes in a variety of autoimmune models.”^[6] Clearly the manipulation and mutation of this enzyme holds great promise for being able to fight a variety of diseases in the body.

References

^ "PCEM2 Révisions Biochimie métabolique: Chapitre 13 - Les glycoprotéines" [PCEM2 Metabolic Biochemistry Revision: Chapter 13 - Glycoproteins] (in French).
^ ^a ^b ^c ^d Davies, G; Henrissat, B (15 September 1995). "Structures and mechanisms of glycosyl hydrolases". Structure 3 (9): 853–59. doi:10.1016/s0969-2126(01)00220-9.
^ Piszkiewicz, D; Bruice, T.C. (10 April 1968). "Glycoside hydrolysis. II. Intramolecular carboxyl and acetamido group catalysis in 13-glycoside hydrolysis". Journal of the American Chemical Society 90 (8): 2156–63. doi:10.1021/ja01010a038.
^ ^a ^b Koshland, D.E. (November 1953). "Stereochemistry and the mechanism of enzymatic reactions". Cambridge Philosophical Society: Biological Reviews 28 (4): 416–436. doi:10.1111/j.1469-185X.1953.tb01386.x.
^ Plante, O; Palmicci, E (2001). "Seeberger Oligosaccharide Synthesis with Glycosyl Phosphate and Dithiophosphate Triesters as Glycosylating Agents". Journal of the American Chemical Society 123 (39): 9545–54. doi:10.1021/ja016227r.
^ Albert, H; Collin, M; Dudziak, D (30 September 2008). "In vivo enzymatic modulation of IgG glycosylation inhibits autoimmune disease in an IgG subclass-dependent manner". Proceedings of the National Academy of Science of the USA. 105.39: 15005–15009. doi:10.1073/pnas.0808248105.

English Journal

Impact of heparanase on renal fibrosis.

Masola V1, Zaza G2, Onisto M3, Lupo A4, Gambaro G5.
Journal of translational medicine.J Transl Med.2015 Jun 4;13:181. doi: 10.1186/s12967-015-0538-5.
Tubulo-interstitial fibrosis has been recognized as the hallmark of progression of chronic kidney disease, but, despite intensive research studies, there are currently no biomarkers or effective treatments for this condition. In this context, a promising candidate could be heparanase-1 (HPSE), an en
PMID 26040666

Functional expression and molecular characterization of Culex quinquefasciatus salivary α-glucosidase (MalI).

Suthangkornkul R1, Sirichaiyakul P1, Sungvornyothin S2, Thepouyporn A1, Svasti J3, Arthan D4.
Protein expression and purification.Protein Expr Purif.2015 Jun;110:145-50. doi: 10.1016/j.pep.2015.02.018. Epub 2015 Mar 5.
Salivary α-glucosidases (MalI) have been much less characterized when compared with midgut α-glucosidases, which have been studied in depth. Few studies have been reported on the partial characterization of MalI, but no clear function has been ascribed. The aim of this study is to purify and chara
PMID 25746591

A Conserved Di-Basic Motif of Drosophila Crumbs Contributes to Efficient ER Export.

Kumichel A1,2, Kapp K1, Knust E1.
Traffic (Copenhagen, Denmark).Traffic.2015 Jun;16(6):604-16. doi: 10.1111/tra.12273. Epub 2015 Apr 14.
The Drosophila type I transmembrane protein Crumbs is an apical determinant required for the maintenance of apico-basal epithelial cell polarity. The level of Crumbs at the plasma membrane is crucial, but how it is regulated is poorly understood. In a genetic screen for regulators of Crumbs protein
PMID 25753515

Japanese Journal

Award Review : Biological Analysis of the Microbial Metabolism of Hetero-Oligosaccharides in Application to Glycotechnology

YAMAMOTO Kenji
Bioscience, Biotechnology, and Biochemistry 76(10), 1815-1827, 2012-10-00
NAID 40019462242

Synthesis of neoproteoglycans using the transglycosylation reaction as a reverse reaction of endo-glycosidases

ENDO Masahiko,KAKIZAKI Ikuko
Proceedings of the Japan Academy, Series B 88(7), 327-344, 2012
… In the transglycosylation reaction of bovine testicular hyaluronidase, which is an endoglycosidase, glycosaminoglycans (hyaluronan and chondroitin sulfates) release disaccharide (uronic acid-N-acetylhexosamine) moieties from non-reducing terminal sites, and then the liberated disaccharides are transferred immediately to the non-reducing termini of other glycosaminoglycan chains. …
NAID 130001924753

Cell surface expression and internalization of the murine erythroid AE1 anion exchanger tagged with an extracellular FLAG epitope

Wang Chen-Chi,Sato Kota,Otsuka Yayoi,Inaba Mutsumi
Japanese Journal of Veterinary Research 59(4), 157-164, 2011-11-00
… Interestingly, the form of the protein with an endoglycosidase H (endoH)-sensitive N-glycan was the major component of EGFP-tagged and wild-type AE1. …
NAID 120003596824