CHEMISTRY GLOSSARY

maltase    →   maltaza

Maltase is an enzyme that catalyzes the hydrolysis of the disaccharide maltose into two molecules of glucose.

maltose    →   maltoza

Maltose (malt sugar) is a disaccharide which is obtained with hydrolytic decomposition of starch in the presence of enzyme amylase. Maltose is composed of two glucose molecules linked by an α(1→4)-glycosidic linkage. Maltose has an alpha acetal.

pepsin    →   pepsin

Pepsin is the enzyme of gastric juice which razes proteins; it is also used as medicine.

glycogen    →   glikogen

Glycogen (animal starch) is a polysaccharide that serves the same energy storage function in animals that starch serves in plants. Dietary carbohydrates not needed for immediate energy are converted by the body to glycogen for long term storage (principally in muscle and liver cells). Like amylopectin found in starch, glycogen is a polymer of α(1→4)-linked subunits of glucose, with α(1→6)-linked branches. Glycogen molecules are larger than those of amylopectin (up to 100 000 glucose units) and contain even more branches. Branch points occur about every 10 residues in glycogen and about every 25 residues in amylopectin. The branching also creates lots of ends for enzyme attack and provides for rapid release of glucose when it is needed.

high fructose corn syrup    →   visoko fruktozni kukuruzni sirup

High fructose corn syrup (HFCS) is commonly used in place of sugar in foods and drinks. Corn starch is hydrolyzed to glucose, which is then treated with glucose isomerase to produce a fructose-rich mixture. HFCS is available in a number of forms, named according to the percentage of fructose they contain, HFCS-55 for instance contains 55 % fructose and 45 % glucose. The enhanced sweetness, low cost and ease of use are the main reasons why manufacturers now prefer to use high fructose corn syrup instead of sugar.

lactose    →   laktoza

Lactose (milk sugar) is a disaccharide comprising one glucose molecule linked to a galactose molecule by an β(1→4)-glycosidic linkage. Lactose has a beta acetal. Lactose is manufactured by the mammary gland and occurs only in milk (from 4 % to 7 %). Lactose intolerance is a common medical condition that results in diarrhea, abdominal pain, and flatulence and is caused by reduced or absent activity of enzyme lactase.

Like cellobiose and maltose, lactose is a reducing sugar. All reducing sugar undergo mutarotation in aqueous solution. The equilibrium mixture at 20 °C is composed of 62.7 % β-lactose (β-D-galactopyranosyl-(1→4)-β-D-glucopyranose) and 37.3 % α-lactose (β-D-galactopyranosyl-(1→4)-α-D-glucopyranose).

precursor    →   prekursor

Precursor means any chemical reactant which takes part at any stage in the production by whatever method of a toxic chemical. This includes any key component of a binary or multicomponent chemical system. A zymogen (or proenzyme) is an inactive enzyme precursor.

proteases    →   proteaze

Proteases are enzymes which raze proteins during digestion.

protelysis    →   proteoliza

Proteolysis is hydrolytic decomposition of proteins with enzymes, for example trypsin.

ptyalin    →   ptijalin

Ptyalin is an older name for saliva enzyme amilase which razes starch and turns it into sugar.