Comparison of Protein Composition of Normal and Quality Protein Maize

The endosperm of normal maize is predominates with the zein proteins (prolamins and prolamin-like) which are primarily responsible for poor quality of protein. To overcome such problems researchers have developed quality protein maize (QPM) by modifying the protein profile of normal maize so the present study was taken up to understand the comparative protein composition in kernels of normal and quality protein maize. For this purpose six maize genotypes were evaluated for tryptophan content, endosperm protein and protein fractions viz. albumin and globulins, prolamins, prolamin-like, glutelin-like and glutelins. Approximately 47% higher tryptophan content was observed in QPM genotypes which are result of endosperm modification that alter maize endosperm amino acid profile and composition of maize endosperm protein. In addition, QPM genotypes also had higher albumin, globulins and glutelins fractions as compared to the normal maize. The normal genotypes showed approximately 60% of total protein as zein protein as compared to QPM genotypes having 30% of total protein as zein protein. The presence of opaque-2 gene in QPM genotypes, encodes a transcription factor which reduces the transcription and expression of 22kD alpha-zein protein and increases the non-zein protein fractions. It was concluded that QPM maize possess an improved amino acid profile and endosperm protein composition which ensures the nutritional security.