Aliphatic semisynthetic amino terminal variants of myoglobin: enrichment with carbon-13, determination and interpretation of terminal pK values and motions
The synthesis of a series of myoglobins substituted in the amino terminal residue to provide variation in the aliphatic nature of the side chain and enrichment in /sup 13/C was accomplished by semisynthetic methods. The replacements of valine, the native first residue, included /sup 13/C enriched glycine, alanine, valine, leucine, and isoleucine. The products were extensively characterized and found to be virtually indistinguishable by most physical methods. /sup 13/C NMR spectroscopy showed significant differences in the amino terminal pK value, ranging from 7.72 for myoglobin to 7.15 for myoglobin. Consideration of the electrostatic effects of the charge array indicated a balance of interactions at this site not significantly altered by variations in the side chain. By examination of the crystal structure, consideration of earlier work regarding the interactions of the side chain of Leu-2, and data regarding the motions of the terminal residue, it was concluded that the interaction of the side chain of the first residue with the hydrophobic cluster formed primarily by close contact of invariant residues Leu-2 and Leu-137 was the primary cause for the reduction in the terminal pK values seen for the larger aliphatics. By restricting the freedom of the residue, this interaction limits the available hydration volume, and consequently favors the unprotonated form of the amine. The concurrent observation of both functional elements in the series of ..cap alpha.. amino terminal residues brings out the interrelated consequences for the two categories of solvent interactions controlling structural and functional properties in a graded way.
- Research Organization:
- Indiana Univ., Bloomington (USA)
- OSTI ID:
- 5819796
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Bioorganometallic chemistry. 8. The molecular recognition of aromatic and aliphatic amino acids and substituted aromatic and aliphatic carboxylic acid guests with supramolecular ({eta}{sup 5}-pentamethylcyclopentadienyl)rhodium - nucleobase, nucleoside, and nucleotide cyclic trimer hosts via non-covalent {pi}-{pi} and hydrophobic interactions in water: Steric, electronic, and conformational parameters
Structural significance of the amino terminal residues in human hemoglobin
Related Subjects
ALANINES
NMR SPECTRA
GLYCINE
LEUCINE
MYOGLOBIN
CHEMICAL PREPARATION
VALINE
CARBON 13
ELECTROPHYSIOLOGY
MOLECULAR STRUCTURE
TRACER TECHNIQUES
AMINO ACIDS
CARBON ISOTOPES
CARBOXYLIC ACIDS
EVEN-ODD NUCLEI
GLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSIOLOGY
PIGMENTS
PORPHYRINS
PROTEINS
SPECTRA
STABLE ISOTOPES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques