dna sequencing comprising contacting a template dna with a primer homologous to a specific sequence on a target dna in the presence of a dna polymerase and an effective amount of proline thp b and or thp a under conditions allowing dna sequencing a commonly used cycle dna sequencing protocol known as sanger or dideoxy sequencing method typically includes isolating double stranded template dna separating it into its component single strands adding a sequencing primer homologous to a sequence of nucleotides on the target dna and performing a cycled primer extension of said primer on the target dna the cycled primer extension is performed in four paralleled reactions each including a small amount of a dideoxynucleotide triphosphate either ddatp ddctp ddgtp or ddttp along with a molar excess of the four deoxynucleotide triphosphates dntps normally required for dna synthesis i e datp dctp dgtp or dttp the growth of the extended dna chain is stopped once a ddntp molecule is incorporated into it thus generating series of extension products of various lengths when these extension products of the four extension reactions are separated side by side for example on a polyacrylamide gel a pattern is obtained by using a labeled primer or labeled ddntp typically radioactive or fluorescent this pattern can be monitored for example by autoradiography fluorescence detectors etc and the dna sequence can be determined cycle dna sequencing also involves cycle primer extension thus the sequencing outcome is influenced by similar criteria as mentioned above for pcr the degree of template dna and primer denaturation as well as the polymerase performance are of crucial importance for the sensitivity and accuracy of a sequencing reaction the exact reaction conditions for performing a cycle dna sequencing method and the effective concentrations of the added osmoprotectant vary depending.