Structural study of phosphomannan of yeast-form cells of Candida albicans J-1012 strain with special reference to application of mild acetolysis

Characterization of β-1,2-Mannosyltransferase in Candida guilliermondii and Its Utilization in the Synthesis of Novel Oligosaccharides

“…Therefore, we can also assign through the H-1-H-2-correlated cross-peak C2 and the NOE cross-peak C2Ј between the H-2 of Man-D and the H-1 of Man-C. Additionally, we could find the NOE cross-peak D2Ј between the H-2 of Man-D and the H-1 of Man-E, of which the signal, 4.764 ppm, corresponds to the ␤-1,2-linked mannose unit (10,11,17). Using this procedure, we could sequentially assign the H-1 signal from Man-A to Man-E as A2-A2Ј-B2-B2Ј-C3-C3Ј-(or -C2-C2Ј-)-D2-D2Ј-E2.…”

“…Therefore, we assumed that Man-D of SagMan 6 is substituted by a ␤-1,2-linked mannose unit, Man-E. It has been shown that the H-1 signal of an ␣-linked mannose unit substituted by a single ␤-1,2-linked unit causes a downfield shift (⌬␦ ϭ 0.09 -0.12 ppm) (10,11,17) and that the ␤-1,2-linked mannose units gave H-1-H-5-correlated cross-peaks in a characteristic region (14,17,18). In the spectrum of SagMan 6 , the H-1 proton of Man-D at 5.239 ppm appeared at 0.1 ppm more downfield than that of SaMan 5 at 5.129 ppm, and there is a ␤-mannose specific H-1-H-5-correlated cross-peak.…”

“…Although KaMan 4 , AaMan 6 , and SaMan 6 can also possibly act as the acceptors of both the ␤-1,2-mannosyltransferase IV and an ␣-1,2-mannosyltransferase judging from the structure of C. guilliermondii mannan, their enzyme reaction products, designated as KagMan 5 , AagMan 7 , and SagMan 7 , exhibited a signal at about 4.76 ppm in the 1 H NMR spectra (data not shown). Therefore, it is apparent that the transferred mannose unit is attached to each substrate with a ␤-1,2 linkage (10,11,17). Since these ␤-1,2 linkagecontaining branched oligosaccharides have not been found in the acetolysate of yeast mannans, it is reasonable to say that we could prepare novel oligosaccharides using the ␤-1,2-mannosyltransferase IV of C. guilliermondii.…”

“…The H-1 and H-2 signals of SaggMan 7 were sequentially assigned from Man-A to Man-F, A2-A2Ј-B2-B2Ј-C3-C3Ј-(or -C2-C2Ј-)-D2-D2Ј-E2-E2Ј-F2. It has been shown that the H-1 signal of an ␣-linked mannose unit substituted by two consecutive ␤-1,2-linked units causes an upfield shift (⌬␦ ϭ 0.02 ppm) (10,11,17,18). The H-1 proton of the Man-D of SaggMan 7 at 5.216 ppm appeared at about 0.02 ppm upfield from that of SagMan 6 at 5.239 ppm.…”

“…One is the ␤-1,2-linked mannooligomer, which is located in a phosphodiesterified oligosaccharide moiety, as the common epitope in the mannans of several Candida species (4 -9). The second type is ␤-1,2-linked mannose units attached to the nonreducing terminal of the ␣-1,2-linked oligomannosyl side chains in the mannans of Candida albicans serotype A (10,11), Candida tropicalis (12), and Candida glabrata (13). These two ␤-1,2 linkagecontaining epitopes have been identified as corresponding to antigenic factors 5 (14) and 6 (15), respectively.…”