Nerve growth factor from mouse submaxillary gland: amino acid sequence

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Nerve growth factor (NGF) is crucial for neuronal development and survival.
• Understanding the primary structure of NGF is essential for elucidating its function.
• Previous studies provided limited information on the complete amino acid sequence of mouse submaxillary gland NGF.

Purpose of the Study:

• To determine the complete amino acid sequence of 2.5S nerve growth factor (NGF) from male mouse submaxillary glands.
• To establish the primary structure, including subunit composition, molecular weight, and disulfide bond arrangement.
• To correlate the primary sequence with biochemical properties like amino acid composition and isoelectric point.

Main Methods:

• Peptide digestion using various enzymes (tryptic, chymotryptic, thermolytic, peptic).
• Analysis of modified growth factor forms (S-carboxymethyl-, S-aminoethyl-, and native).
• Amino acid sequencing and alignment of resulting peptides.
• Determination of disulfide bond linkages through combined enzymatic digestions.
• Assignment of side-chain amides.

Main Results:

• The primary subunit of mouse NGF consists of 118 amino acids, starting with serine and ending with arginine.
• The calculated molecular weight of the subunit is 13,259, and the native dimer is 26,518.
• Three disulfide bonds were unambiguously aligned: I-IV, II-V, and III-VI.
• A closed loop of 14 amino acids was identified, containing disulfide bonds II-V and III-VI.
• The distribution of aspartic and glutamic acid amides was determined, consistent with an isoelectric point of 9.3.

Conclusions:

• The complete primary structure of mouse 2.5S NGF has been elucidated.
• The determined sequence and molecular weight align with experimental measurements.
• The disulfide bond arrangement and amide distribution provide insights into NGF's tertiary structure and properties.