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.
Numata
Munenori
M
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan.
Matsumoto
Takahiro
T
Umeda
Mariko
M
Koumoto
Kazuya
K
Sakurai
Kazuo
K
Shinkai
Seiji
S
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