BCH 261 Lecture Notes - Lecture 5: Lactose Permease, Enolase, Dna Replication

• School: Ryerson University
• Department: Biochemistry
• Course: BCH 261
• Professor: Costin Antonescu

Document Summary

In fischer projections, left and right side are going towards you so look which side has the heavier atom. At acidic ph, the carboxyl group is protonated and the amino acid is in the cationic form. At neutral ph, the carboxyl group is deprotonated but the amino group is protonated. The net charge is zero; such ions are called zwitterions. At alkaline ph, the amino group is neutral nh2 and the amino acid is in the anionic form. When amino acids are joined into a polypeptide, only some of the chemical groups remain ionizable. Average mw of aa is 138 da. In biology use: 128 da (smaller aa predominate in cells) In proteins, average mw for residues: 128 - 18 (mw h2o) = 110 da. Therefore the #residues in a protein = mw protein / 110. Or the mw of a protein = number of residues x 110 da.