11 . Net Electric Charge of Peptides A peptide has the sequence Glu - His - Irp - Ser - Gly - Leu - Arg - Pro - Gly AI PH 3 = + 2 PH 8 = 0 PHIL = -

Hi, This is from metabolic biochemistry. I already have the answers in red, I just need an explanation of how you get those answers and how do you predict what Amino Acids were used to make up the compound/toxin.

11 . Net Electric Charge of Peptides A peptide has the sequenceGlu - His - Irp - Ser - Gly - Leu - Arg - Pro - GlyAI PH 3 = + 2 PH 8 = 0 PHIL = - 19( a ) What is the net charge of the molecule at PH1 3 . 8, and I1? ( Use pk, values for sidechains and terminal aming and carboxyl groups as given in Table 3 - 1 . )( b) Estimate the pl for this peptide .BI P1 = 7.812 . Ismelectric Point of Pepsin Pepsin is the name given to a mix of several digestive*enzymes secreted ( as larger precursor proteins ) by glands that line the stomach . Theseglands also secrete hydrochloric acid , which dissolves the particulate matter in food .allowing pepsin to enzymatically cleave individual protein molecules . The resultingmixture of food , HEY , and digestive enzymes is known as chyme and has a PH near 1 . 5What pl would you predict for the pepsin proteins ?" What functional groups must be presentto confer this pl on pepsin ?" Which amino acids in the proteins would contribute suchgroups"!`PL = 1 : Carboxylate groups : Asp and GLU