Spontaneous formation of helical structures from phospholipid-nucleoside conjugates.
Phospholipid-nucleoside conjugates containing two myristoyl groups and a nucleotidyl group, collectively designated as dimyristoyl-5'-phosphatidylnucleosides, were enzymatically synthesized and their self-organization, morphology, and physicochemical properties investigated. The dimyristoyl-5'-phosphatidylnucleosides spontaneously assembled to form various types of helical strands. Neutral and alkaline solutions of dimyristoyl-5'-phosphatidyladenosine (DMPA) produced multihelical strands. The multihelical strand consisted of several single helical strands of approximately 50 A in diameter and helical pitch approximately 100 A. DMPA produced cigar-like scrolls (tubular structures) in acidic solution, which consisted of many double-helical strands aligned parallel to each other. Diacyl-5'-phosphatidyladenosine with a shorter chain length as long as an alkyl group, dilauroyl-5'-phosphatidyladenosine (DLPA), didecanoyl-5'-phosphatidyladenosine (DDPA), and dioctanoyl-5'-phosphatidyladenosine (DOPA) formed extended tape structures having double-helical strands aligned parallel. Dimyristoyl-5'-phosphatidylcytidine (DMPC) produced network structures at an early stage, which were slowly transformed into multihelical strands. The multihelical strands contained some single-helical strands of approximately 55 A in diameter and helical pitch approximately 150 A. DMPA produced no definite helical structure in acidic solution but rather large lamellar structures. Dimyristoyl-5'-phosphatidyluridine (DMPU) produced crystalline platelet structures of approximately 1000 A in width in both alkaline and acidic solution. A 1:1 mixture of DMPA and DMPU formed a new hybrid helical strand having a wide and thick ribbon structure of approximately 300 A in diameter and helical pitch approximately 2000 A. The formation of different helical strands and effects of chain lengths of alkyl groups and a nucleotidyl group in phospholipid-nucleoside conjugates on that of helical strands in aqueous solution are discussed.
Itojima
Y
Y
Graduate School of Science and Technology, Kobe University, Japan.
Ogawa
Y
Y
Tsuno
K
K
Handa
N
N
Yanagawa
H
H
D000814:Aniline Compounds / Q000737:chemistry; D001792:Blood Platelets / Q000737:chemistry / Q000648:ultrastructure; D002942:Circular Dichroism; D004295:Dihydroxyphenylalanine / Q000737:chemistry; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004338:Drug Combinations; D046911:Macromolecular Substances; D009690:Nucleic Acid Conformation; D010712:Phosphatidic Acids / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry*; D012263:Ribonucleosides / Q000737:chemistry*; D013329:Structure-Activity Relationship
D000814:Aniline Compounds; D004338:Drug Combinations; D046911:Macromolecular Substances; D010712:Phosphatidic Acids; D010715:Phosphatidylglycerols; D012263:Ribonucleosides; D004295:Dihydroxyphenylalanine; C050795:N,N-dimethyl-4-anisidine; C042076:1,2-dilauroylphosphatidic acid; D004134:Dimyristoylphosphatidylcholine