Aspartic acid hemoglobin

Alpert has shown [47] that poly(succinimide)-silica can be further hydrolyzed to poly (aspartic acid)-silica or condensed with [3-alanine in aqueous solution to form a covalently bonded copolymer of 2-carboxyethyl aspartamide and aspartic acid. The content of carboxyl groups generated by this way has not been quantified directly, but the cation-exchange hemoglobin capacity has been measured for a series of the packings. Thus, the optimal concentration of poly(succinimide) used in the synthesis was found to be 2 5%. 

The primary structure of a protein is the sequence of residues in the peptide chain. Aspartame consists of phenylalanine (Phe) and aspartic acid (Asp), and so its primary structure is Phe-Asp. Three fragments of the primary structure of human hemoglobin are... 

Imamura, T., Fujita, S., Ohita, Y., Hanada, M., and Yanase, T., Hemoglobin Yoshizuka (GIO (108)/3 Asparagine— Aspartic Acid) a new variant with a reduced oxygen affinity from a Japanese family. J. Clin. Invest. 48, 2341-2348 (1969). 

Hemoglobin Swan River differs in having GGC instead of GAC as the sixth codon. The corresponding amino changes from aspartic acid to glycine. 

The kinetic products they obtained contained covalently bound chromium with Cr(III) to protein ratios of 1.0 for myoglobin and 4.0 for hemoglobin. These Cr(III)-protein complexes retained spectral properties and oxygen and CO binding properties identical to the untreated protein. They concluded that the Cr(III) was not bound at or near the sixth axial position and that the Cr(II) probably passed one electron to the Fe(III) via an exposed porphyrin edge. It was concluded that the chromium(III) was attached to amino acids 32-42 and/or 57-63 which contain close or adjacent aspartic acid and glutamic acid residues. 

Many protein molecules are composed of more than one subunit, where each subunit is a separate polypeptide chain and can form a stable folded structure by itself. The amino acid sequences can either be identical for each subunit (as in tobacco mosaic virus protein), or similar (as in the a and )3 chains of hemoglobin), or completely different (as in aspartate transcarbamylase). The assembly of many identical subunits provides a very efficient way of constructing... 

Back to the bench. A protein chemist told a molecular geneticist that he had found a new mutant hemoglobin in which aspartate replaced lysine. The molecular geneticist expressed surprise and sent his friend scurrying back to the laboratory, (a) Why did the molecular geneticist doubt the reported amino acid substitution (b) Which amino acid substitutions would have been more palatable to the molecular geneticist ... 

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