What is the biologically-preferred stereochemistry and ionization states for the pentagon-peptide CANDY at a pH of 7?

Bb.45.

Phosphate buffers are commonly used to mimic biological systems. Given that phosophoric acid is a triprotic acid with three pKas (2.12, 7.21, and 12.32), why do you think this is? What are the dominant buffering compounds present in a phosphate buffer near physiological pH?

Calculate the pI of the peptide KLMRDSP (pKa = 3.5, 3.9, 9.5, 10.0, 12.5).

The amino acid glycine is often used as an ingredient in buffers for biochemistry experiments. The amino group of glycine has a pKa of 9.6. Glycine exists in either a protonated form (-NH3+) or a free base (-NH₂). a) In what pH range can glycine be used as an effective buffer? b) In a 0.1M solution of glycine at pH 9.0, what fraction has its amino group in the protonated form? c) When 99% of the glycine is in the protonated from, what is the numerical relation between the pH of the solution and the pKa of the amino group?

Hypoglycin A, an amino acid derivative found in unripened lychee, is an acutely toxic compound that produces seizures, coma, and sometimes death in undernourished children when ingested on an empty stomach. (a) Draw the neutral, positively charged, and negatively charged forms of hypoglycin A. (b) Which form predominates at pH = 1, 6, and 11? (c) What is the structure of hypoclycin A at its isoelectric point?

What is the molecular basis for the observation that the overall charge on a protein becomes increasingly positive as pH drops and more negative as pH increases?

At which pH would the peptide with the amino acid sequence 'KEYHR' be found in an IPG (Immobilized pH gradient) strip after successful isoelectric focusing. Show calculation. lonizable groups Alpha amine group of K Side chain group of K Side chain group of E Side chain group of Y Side chain group of H Side chain group of R Alpha carboxylic acid group of R pka 8.95 10.53 4.25 10.07 6 12.48 2.17

What is the net charge on the peptide RHTLE at pH 12.5?

What is the charge on the following peptide at standard biochemical pH? S-Y-D-F-K-I-V-F-L-L +2 -1 0 0 0-2 O +1