the scope of this invention are other obvious modifications of these peptides the one letter symbol for the amino acids used herein is well known in the art for convenience the relationship of the three letter abbreviation and the one letter symbol for amino acids is as follows ______________________________________ala a leu larg r lys kasn n met masp d phe fcys c pro pgln q ser sglu e thr tgly g trp whis h tyr yile i val v______________________________________ the novel peptides of the invention can be prepared by well known synthetic procedures for example the peptides can be prepared by the well known merrifield solid support method see merrifield 1963 j arner chem soc 85 2149 2154 and merrifield 1965 science 150 178 185 this procedure though using many of the same chemical reactions and blocking groups of classical peptide synthesis provides a growing peptide chain anchored by its carboxyl terminus to a solid support usually cross linked polystyrene or styrenedivinylbenzene copolymer this method conveniently simplifies the number of procedural manipulations since removal of the excess reagents at each step is effected simply by washing of the polymer alternatively these peptides can be prepared by use of well known molecular biology procedures dna sequences encoding the peptides of the invention can be synthesized readily because the amino acid sequences are disclosed herein these dna sequences are a further aspect of the subject invention these genes can be.