This presentation is on topic glucoisomerase. In this presentation, function structure and application are well described. This presentation is public and can be downloaded by anyone. My aim is to help students.

1. INSTITUTE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF BIOTECHNOLOGY
PROTEIN AND ENZYME ENGINEERING
TOPIC:GLUCOISOMERASE
PRESENTED BY: AKSHAY MISHRA
ROLL NO: 201411029009
BUNDELKHAND UNIVERSITY, JHANSI

2. INTRODUCTION TO GLUCOISOMERASE:
• The other name for glucose isomerase are D-xylose ketol isomerase, xylose
isomerase (XI), xylose keto isomerase, and xylose ketol-isomerase.
• This enzyme is an intramolecular oxidoreductase that can interconvert
aldoses and ketoses.
• Glucose isomerase reversibly isomerizes D-glucose and D-xylose to D-
fructose and D-xylulose, respectively.
• It is one of the three most commonly produced industrial enzymes, along
with amylase and protease.

3. ENZYME NOMENCLATURE:
• IUBMB ENTRY – EC 5.3.1.5
• SYSTEMATIC NAME of this enzyme class is D-xylose aldose-ketose-isomerase.
• This enzyme belongs to the family of isomerases.

4. FUNCTION:
• Catalyze the reversible isomerization of D-glucose and D-xylose to D-fructose and
D-xylulose, respectively.
• Exhibits activity against a broad spectrum of sugar of 12 substrates, including D-
ribose, L-rhamnulose, L-arabinose, and D-allose, although the substrate specificity
of GIs can vary depending on the source strain or organism.
• GI is known to exhibit the highest activity in the presence of divalent metal ions
such as Mg2+, Mn2+, and Co2+ while inhibitor as xylitol, mannitol etc.
• Efficiently perform at ph 7 to 9 and temperature of 60 to 80 degrees Celcius.

5. REACTION MECHANISM:
• The catalytic reaction of GI occurs in three major steps: (i) ring opening, (ii)
isomerization, and (iii) ring closure.
• An open ring state, and a closed ring form product is created after isomerization via a
hydride shift.

6. Figure: Isomerization mechanism of GI. (a) Three major steps
are involved in the configuration change from D-glucose to D-
fructose catalyzed by GI. (b) Hydride shift mechanism of GI.

7. STRUCTURE:
• GI consists of a TIM barrel-like domain and an extended α-helix domain
(Figure A, B) which are assembled into a functional tetramer (Figure C) .
The substrate-binding pocket is formed by two protomers and the GI
active site is located on the TIM barrel fold (Figure C). The GI exists as a
tetramer with 222 crystallographic symmetry and includes four active sites
for substrate isomerization.
• The typical GI active site contains two sites, M1 and M2, for metal binding.

8. Crystal structure of the GI from Streptomyces rubiginosus
(SruGI). (a) GI protomer consists of a TIM-barrel domain and an
extended α-helical domain. (b) The extended α-helical domain
interacts with the TIM barrel domain from the neighboring GI
molecule. (c) Tetrameric GI shows 222 symmetry.

9. SOURCE ORGANISMS OF GI:
• Streptomyces griseofuscus
• Streptomyces murinus (SmGI)
• Thermus caldophilus
• Thermotoga neapolitana

10. APPLICATION OF GI:
• GI plays an important role in sugar metabolism, fulfilling nutritional requirements
in bacteria.
• GI is an important industrial enzyme for the production of high-fructose corn
syrup(HFCS) and bioethanol.
• Products containing Xylose-Isomerase are sold as over-the-counter dietary
supplements to combat fructose malabsorption, primarily in Europe and under
brand names including Fructaid, Fructease and Fructosin.
• GIs can also produce rare sugars that are used in food or medicinal products.

11. REFERENCES:
• MDPI review by Ki Hyun Nam
• Wikipedia
• PubMed

12. THANK YOU