End of notes. Questions coming soon of maltose can be measured using a colorimet

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End of notes. Questions coming soon

of maltose can be measured using a colorimetric assay: that is, c se with a certain reagent that causes a color change. The reagent in this assay is DNS Lab Exercise 4B ombi ining adstances in urine, DNS assay is commonly used to quantitate carbohydrate levels in bl well as detecting alpha amylase activity (3,5-d -dintrosalicylic acid) which is vellow in color. First introduced to detect reducinge In an alkaline solution, reducing sugars form different reagents (e.g., Benedicts reagent, aldehyde or ketone groups which can then (eg. Benedicts reagent, dinitrosalicylic acid or DNS). Unlike Benedicts for detecting the presence of reducing sugars, reaction between DNS and a reducing sugar CH20H OH 0H H OH Maltose Maltose Maltonic Acid OH (reduced)(oxidised) Heat & Alkaline condition NH2 0 Dinitrosalicylic acid 3-Amino-5-nitrosalicylic acid Reduced DNS (Orange to Red) DNS (Yellow) results in a soluble and colored product. Maltose participates in an oxidation-reduction reaction with DNS due to the presence of a carbonyl group (C-O). DNS is reduced into 3-amino, S-nitrosalicylic acid (can be referred to simply as reduced DNS) and maltose gets oxidized and becomes maltonic acid. This reaction causes a change in color from vellow to orange/red due to the presence of reduced DNS. The change in color results in a change in absorption of lign and absorbance is measured in a spectrophotometer at a wavelength of 540 nm. The intensity color from the reaction is proportional to the concentration of maltose and is used to estimate concentration of maltose in any given solution. of The concentration or aiyase heroe absorbance can be used to determine the The concentration of activity of the enzyme, amylase. Therefore, absor abhorbanceg cardh is activity, i.e., conditionts) at which enymes have the highest conditionts) a can be u (Optimal condition). ave the highest activity

Explanation / Answer

Answer. Majority of the sugars are reducing except the sucrose.

Reducing sugars possess a free C1 atom that can unite with the other molecule. The reducing sugars give positive test with the Benedict's solution and the Fehling's solution. Sucrose gives negative test with them.

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