Discussion on Determination of Protein Content by Amino Acid and Nitrous Acid Method in General High School Chemistry Curriculum Standards
WANG Yong-Sen1**, YE Chang-Jun2, JIN Cong-Wu3, SANG Shou-De4
1. Beijing No.9 High School, Beijing 100041, China; 2. Beijing No.4 High School,Beijing 100034, China; 3. The Experimental High School Attached To Beijing Normal University, Beijing 100032, China; 4. Beijing No.80 High School, Beijing 100102, China
Abstract The method in the General High School Chemistry Curriculum Standards to measure protein concentrations was based on the determination of free amino groups (as in amino acids or proteins) by measuring the volume or pressure of nitrogen gas formed by reaction with nitrous acid, which was not applicable to proteins with the nitrogen-containing group in the side chain and auxiliary group. Therefore, this method could not be used to detect the protein content, but could be used to determine the hydrolysis degree of proteins. By comparing various methods to quantitatively determine protein content, such as the Kjeldahl method, UV absorbance method, biuret method, bicinchoninic acid (BCA) method, folin-phenol reagent method, and Coomassie brilliant blue (CBB) binding method, the authors suggested that the biuret method should be adopted in general high school chemistry teaching.
WANG Yong-Sen, YE Chang-Jun, JIN Cong-Wu, SANG Shou-De. Discussion on Determination of Protein Content by Amino Acid and Nitrous Acid Method in General High School Chemistry Curriculum Standards[J]. Chinese Journal of Chemical Education, 2023, 44(9): 120-124.
