MALDI- TOF Analysis of RNase A
Department of Biochemistry, Sri Venkateswara University, Tirupati, Andhra Pradesh, India
Dr. Eswari Beeram, Department of Biochemistry, Sri Venkateswara University, Tirupati, Andhra Pradesh, India.
Keywords: MALDI; TOF Analysis
MALDI or Matrix Assisted Laser Desorption /Ionisation is well known technique which is generally used for analysis of proteins. Now it is well known for carbohydrates and lipids and as well as for chemical compounds. Linear mode is generally used for compounds which are easily fragmented where as reflection mode results in better resolution as it doubles the path of ions before reaching the detector. Positive mode is preferred for positive ions and negative mode for negative ions. Phosphoglycerolipids like phosphatidyl serine and phosphatidyl ethanolamine possess negative charge at physiological pH so its identification is preferable at negative mode. RNase A is a basic protein and has positive charge at physiological pH as it possesses pI of 9.6. Above the neutral pH aminoacids possess negative charge and below the neutral pH aminoacids possess positive charge. When RNaseA is subjected to MALDI analysis peptide of 14-17 aminoacids predominates in both positive and as well as in negative linear mode.
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