chromomycin a3 chromomycin a3 chromomycin a3 (cma3) or toyomycin is an anthraquinone antibiotic glycoside produced by the fermentation of a certain strain of streptomyces griseus (no. 7). chromomycin a3 names iupac name (6s,7s)-6--7--4,10-dihydroxy-3-methyl-5-oxo-5,6,7,8-tetrahydroanthracen-2-yl (2,6-dideoxy-4-o-methyl-d-lyxo-hexopyranosyl)-(1→3)-2,6-dideoxy-d-lyxo-hexopyranoside 4-acetate systematic iupac name (12s,14s,15s,16s,32s,34r,35r,36r,52s,54r,55r,56r,72s,73s,92s,94r,95s,96r,112r,114r,115r,116r)-73--14,35,55,78,79,114-heptahydroxy-115-methoxy-14,16,36,56,77,96,116-heptamethyl-71-oxo-71,72,73,74-tetrahydro-2,4,6,8,10-pentaoxa-1,11(2),3,5(4,2),9(2,4)-pentakis(oxana)-7(2,6)-anthracenaundecaphane-15,95-diyl diacetate other names toyomycin identifiers cas number 7059-24-7 y chembl chembl216639 n chemspider 16735739 y echa infocard 100.027.589 pubchem cid 656673 unii dvw027e7nl y comptox dashboard (epa) dtxsid4046363 inchi inchi=1s/c56h80o27/c1-20-32(78-38-18-35(51(25(6)75-38)83-55(67)68)81-36-15-31(59)50(70-10)24(5)74-36)14-29-12-28-13-30(52(71-11)49(66)44(61)21(2)57)53(48(65)42(28)47(64)41(29)43(20)60)82-39-17-33(45(62)23(4)73-39)79-37-16-34(46(63)22(3)72-37)80-40-19-56(9,69)54(26(7)76-40)77-27(8)58/h12,14,21-26,30-31,33-40,44-46,50-54,57,59-64,69h,13,15-19h2,1-11h3,(h,67,68)/t21-,22-,23-,24-,25-,26+,30+,31-,33-,34-,35-,36-,37+,38+,39+,40+,44+,45-,46-,50+,51+,52+,53+,54+,56+/m1/s1 ykey: vwudfiozfafomw-quooocnjsa-n yinchi=1s/c56h80o27/c1-20-32(78-38-18-35(51(25(6)75-38)83-55(67)68)81-36-15-31(59)50(70-10)24(5)74-36)14-29-12-28-13-30(52(71-11)49(66)44(61)21(2)57)53(48(65)42(28)47(64)41(29)43(20)60)82-39-17-33(45(62)23(4)73-39)79-37-16-34(46(63)22(3)72-37)80-40-19-56(9,69)54(26(7)76-40)77-27(8)58/h12,14,21-26,30-31,33-40,44-46,50-54,57,59-64,69h,13,15-19h2,1-11h3,(h,67,68)/t21-,22-,23-,24-,25-,26+,30+,31-,33-,34-,35-,36-,37+,38+,39+,40+,44+,45-,46-,50+,51+,52+,53+,54+,56+/m1/s1key: vwudfiozfafomw-quooocnjbwkey: vwudfiozfafomw-quooocnjsa-n properties chemical formula c57h82o26 molar mass 1183.257 g·mol−1 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references fluorescence properties in the presence of mg2+ ions, chromomycin a3 binds reversibly to dna, preferentially to contiguous g/c base pairs. when bound to dna, chromomycin a3 has a maximum excitation wavelength of 445 nm (blue), and a maximum emission wavelength of 575 nm (yellow). uses in-vitro membrane-impermeant g/c-specific fluorescent dna-binding dye. in-vitro antibiotic of gram-positive bacteria, through inhibition of the incorporation of pi in the rna. in-vitro anticancer drug that inhibits rna synthesis. evaluation of male fertility: chromomycin a3 and protamines compete for the same binding sites in the dna, so cma3 positivity in spermatozoa reflects protamine deficiency (affecting sperm morphology and decreasing fertility).