NUR ISTIANAH,ST,MT,M.Eng
BIOKATALIS
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Outline
Definition
Types of biocatalyst
Mechanism of enzimatic reaction
DEFINITION
• Enzymes are proteins that are produce d by all living organisms.
• They speed up chemical reactions sele
ctively as part of essential life process
es such as digestion, respiration, meta
bolism and tissue maintenance (highly
specific biological catalysts)
ENZYMES
• Proteinases/protease
They chop up proteins by breaking the amide bonds that join their component amino acids into the protein polypeptide chain
• carbohydrases
lactase breaks down lactose,
maltase breaks down maltose,
pectinase breaks down pectin and
cellulase breaks down cellulose
(alpha-l–4) Amylase breaks down starch to amilum
ENZYMES
ENZYMES
ENZYMES
• some enzymes used to improve an d modify food materials catalyse sy nthetic reactions and substrate inter conversions. for example, glucose o xidase oxidises glucose to gluconic acid, using up oxygen.
• glucose isomerase produce fructose
that is used to make the sweetener,
high fructose corn syrup
ENZYME KINETIC
• working out how much of the chosen e nzyme to use under any particular condi tions to achieve an economical rate an d efficiency of material conversion
• The amount of enzyme is International U nion of Biochemistry Unit (U)
• Bioprocess engineeners work at peak rat es at particular pH values, temperatures and substrate concentrations according t o well-established rules
denaturation
ENZYME STABILITIES
• Enzymes have a finite working life, or half-life, due to i nherent physical instability, the action of antagonists/i nhibitors, and 'poisoning' by contaminants in the rea ction mixture.
• In foods and food technology, physical instability can be induced by the pH and temperature effects outlin ed above, but also by relatively mild forces such as sur face tension in foams and emulsions.
• Most enzyme inhibitors would not be present in foods because they are generally poisonous (e.g. heavy meta ls and organometallic compounds), but many enzyme antagonists and catalytic poisons are common in food s and food raw materials (e.g. respectively, proteolytic enzymes)
ENZYME STABILITIES
• Highly stable enzymes are normally used in pr ocesses that take a long time to complete, suc h as malting and Koji fermentations, or where t he enzyme is part of a diagnostic kit, and has t o survive drying and long storage before use, without losing its standardised activity at manu facture.
• On the other hand, some enzymes used in foo d manufacture are only required to be active f or a short time to scavenge oxygen, to precipi tate milk proteins or to assist ripening.
MECHANISM OF ENZYMATIC REACTION
