Patent ID: 8352193

Claim:
A computer implemented method for deriving probability distributions for a plurality of subject peptide sequences useful in calculating a cumulative ranking for peptide sequences of a protein or protein fragment, said method comprising the steps of: (i) generating a mass spectrum data of a protein or protein fragment; (ii) calculating a first set of m/z values for a first peptide sequence of a length and storing said first set of m/z values in a memory system of said computer; (iii) determining a first abundance value for said first peptide sequence using said first set of m/z values and said mass spectrum data, and erasing said first set of m/z values in said memory system; (iv) calculating a second set of m/z values for a second peptide sequence of the length and storing said second set of m/z values in said memory system; (v) determining a second abundance value for said second peptide sequence using the second set of m/z values and said mass spectrum data; (vi) mathematically combining the first abundance value and the second abundance value thereby forming an abundance combination for said first and second peptide sequences, and erasing said second set of m/z values in said memory system; (vii) iterating steps (iv) to (vi) for additional peptide sequences of the length thereby accumulating an abundance combination for a plurality of peptide sequences of the length; (viii) calculating a subject set of m/z values for each of a plurality of subject peptide sequences of the length and storing said subject sets of m/z values in said memory system; (ix) determining a subject abundance value for each of said plurality of subject peptide sequences of the length using the corresponding subject set of m/z values and said mass spectrum data; and (x) deriving a probability distribution for each of said plurality of subject peptide sequences by autoscaling said corresponding subject abundance value based on said abundance combination for said plurality of peptide sequences of the length, and erasing said subject sets of m/z values in said memory system, wherein at least one of each of said plurality of probability distributions is retrievable for calculating a cumulative ranking for peptide sequences for said protein or protein fragment.