Polysaccharide-polynucleotide complexes (15): thermal stability of schizophyllan (SPG)/poly(C) triple strands is controllable by alpha-amino acid modification.
Schizophyllan (SPG), a beta-1,3-glucan polysaccharide which is known to form macromolecular complexes with certain polynucleotides, was modified by a reductive amination method with alpha-amino acids (Arg, Lys, and Ser). The thermal stability of the complexes as estimated by T(m) was enhanced in SPG-Arg and SPG-Lys conjugates which have pI values higher than the pH of the medium (8.0). The T(m) shift increased with the increase in the percentage of alpha-amino acid introduced and the highest T(m) values attained were 64 degrees C for SPG-Arg conjugate and 62 degrees C for SPG-Lys conjugate, which are higher by 13 and 11 degrees C, respectively, than those of the unmodified SPG+poly(C) complex. In the SPG-Ser conjugate with a pI lower than the medium pH (8.0), the T(m) values decreased with an increase in the percentage of Ser. Formation of the macromolecular complex was no longer detected above 13.2% Ser. The findings indicate that the T(m) values are easily controllable by the type and percentage of the introduced alpha-amino acids. We believe, therefore, that the present conjugates, consisting of naturally originated SPG and alpha-amino acids, provide an important lead for developing nontoxic artificial vectors and to control the affinity with polynucleotides in response to medium pH and temperature.
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan.
Munenori
M
Numata
Takahiro
T
Matsumoto
Mariko
M
Umeda
Kazuya
K
Koumoto
Kazuo
K
Sakurai
Seiji
S
Shinkai
D000596:Amino Acids / Q000737:chemistry*; D001120:Arginine / Q000737:chemistry; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry; D011066:Poly C / Q000737:chemistry*; D012694:Serine / Q000737:chemistry; D012566:Sizofiran / Q000737:chemistry*; D013696:Temperature
D000596:Amino Acids; D011066:Poly C; D012694:Serine; D012566:Sizofiran; D001120:Arginine; D008239:Lysine