http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch27/ch27-1-4-2.html

pKa1= α-carboxyl group, pKa2 = α-ammonium ion, and pKa3 = side chain group. Amino acid, pKa1, pKa2, pKa3, pI. Glycine, 2.34 ... Proline, 1.99, 10.60, ---, 6.30.

https://en.wikipedia.org/wiki/Proline

Proline (symbol Pro or P) is a proteinogenic amino acid that is used in the biosynthesis of proteins. It contains an α-amino group an α-carboxylic acid group  ...

https://www.drugbank.ca/drugs/DB00172

Proline is a non-essential amino acid that is synthesized from glutamic acid. It is an essential ... pKa (Strongest Basic), 11.33, ChemAxon. Physiological Charge ...

http://www.chem.ucla.edu/~rebecca/153A/amino_acids.pdf

Approximate pKa values of ionizable groups of amino acids and peptides. (side chains ... Proline. -1.60. Histidine. -3.20. Aspartic acid -3.50. Glutamic acid -3.50.

https://www.anaspec.com/html/pK_n_pl_Values_of_AminoAcids.html

Proline. 1.99. 10.60. 6.30. Serine. 2.21. 9.15. 5.68. Threonine. 2.15. 9.12. 5.60. Tryptophan. 2.38. 9.39. 5.88. Tyrosine. 2.20. 9.11. 10.07. 5.63. Valine. 2.29. 9.74.

http://www.thinkpeptides.com/aminoacidproperties.html

Nonpolar. Neutral. 1.9. 149.21. 5.74. Phenylalanine. Phe. F. Nonpolar, aromatic. Neutral. 2.8. 165.19. 5.48. Proline. Pro. P. Nonpolar. Neutral. -1.6. 115.13. 6.30.

https://pubchem.ncbi.nlm.nih.gov/compound/Proline

The pKa values of (L)-proline are 1.99 and 10.60, indicating that this compound will exist as a zwitterion in the environment and zwitterions generally adsorb ...

https://www.rose-hulman.edu/~brandt/Chem330/Amino_acids.pdf

non-polar, in a sense proline behaves more like a polar amino acid. Non-polar ... Lysine (pKa = 10.5) and arginine (pKa = 12.5) are basic amino acids that are.

https://www.khanacademy.org/test-prep/mcat/biomolecules/amino-acids-and-proteins1/v/special-cases-histidine-proline-glycine-cysteine

In this video, you'll learn more about what makes histidine, proline, glycine, ... Well, recall that, at a pH below an amino acid's pKa, the amino acid will exist in a  ...

https://proteinstructures.com/Structure/Structure/amino-acids.html

However, the pKa may be modulated by the environment inside the protein, and ... valine, leucine, isoleucine, proline, phenylalanine, cysteine and methionine.