Synthesis of palmitoyl-thioester T-cell epitopes of myelin proteolipid protein (PLP). Comparison of two thiol protecting groups (StBu and Mmt) for on-resin acylation

Thiopalmitoylated Peptides from the Peripheral Nervous System Myelin P0 Protein: Synthesis, Characterization, and Neuritogenic Properties

“…Our results show that the thiol protecting group had to be adjusted to the peptide sequence: Mmt was efficiently used for P0(180−199) thioacylation, but it was not suitable for thiopalmitoylation of P0(152−171) because of a premature deprotection of the Boc protecting group on the ε-NH 2 Lys in the presence of 2% TFA leading to dipalmitoylation. The deprotection of Lys170 ε-NH(Boc) in the presence of diluted TFA was quite unexpected, as in our previous work we obtained, using the same protocol for on-resin acylation, specific mono-palmitoylation of PLP(139−151) using Mmt protecting group for Cys140, even though this peptide possesses two lysines at residues 143 and 150 . It is interesting to note that P0(180−199) possesses a Lys residue at position 183 and no Boc deprotection was observed in the presence of 2%TFA.…”

“…Previously , we showed that the highly acid labile methoxytrityl (Mmt) group was the more versatile protecting group of the thiol for use in the on-resin synthesis of thiopalmitoylated PLP peptides, compared to the t -butylsulfenyl (StBu) protecting group . Here, however, we show that Mmt was not suitable for thiopalmitoylation of P0(152−171), because a side deprotection reaction occurred leading to dipalmitoylation.…”

Thiopalmitoylated Peptides from the Peripheral Nervous System Myelin P0 Protein: Synthesis, Characterization, and Neuritogenic Properties

“…Our results show that the thiol protecting group had to be adjusted to the peptide sequence: Mmt was efficiently used for P0(180−199) thioacylation, but it was not suitable for thiopalmitoylation of P0(152−171) because of a premature deprotection of the Boc protecting group on the ε-NH 2 Lys in the presence of 2% TFA leading to dipalmitoylation. The deprotection of Lys170 ε-NH(Boc) in the presence of diluted TFA was quite unexpected, as in our previous work we obtained, using the same protocol for on-resin acylation, specific mono-palmitoylation of PLP(139−151) using Mmt protecting group for Cys140, even though this peptide possesses two lysines at residues 143 and 150 . It is interesting to note that P0(180−199) possesses a Lys residue at position 183 and no Boc deprotection was observed in the presence of 2%TFA.…”

“…Previously , we showed that the highly acid labile methoxytrityl (Mmt) group was the more versatile protecting group of the thiol for use in the on-resin synthesis of thiopalmitoylated PLP peptides, compared to the t -butylsulfenyl (StBu) protecting group . Here, however, we show that Mmt was not suitable for thiopalmitoylation of P0(152−171), because a side deprotection reaction occurred leading to dipalmitoylation.…”

Lipopeptide epitopes extended by an N ϵ ‐palmitoyl‐lysine moiety increase uptake and maturation of dendritic cells through a Toll‐like receptor‐2 pathway and trigger a Th1‐dependent protective immunity

“…The P 3 CSS moiety was then successfully introduced by Deres et al 22, by Defoort et al 23 and more recently by others 8, 11, and has played a role in attracting attention to the immunological properties of lipidated peptides without external immuno‐adjuvant (reviewed in 1). Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

“…Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

Synthesis of DNA‐Encoded Disulfide‐ and Thioether‐Cyclized Peptides

“…The Fmoc‐Cys(S‐ t Bu)‐OH is broadly used in solid‐phase peptide synthesis and has previously been applied to generate cysteine‐DNA conjugates in order to subsequently link DNA to proteins by expressed protein ligation . While the S‐ t Bu protecting group could efficiently be removed from the cysteine‐DNA conjugates, it has been reported in other studies that elimination of S‐ t Bu can require long reaction times of several hours . In a study by Halpin and co‐workers, Fmoc‐Cys(S‐ t Bu)‐OH was used to synthesize peptide–DNA conjugates on solid phase and they had reported problems to recover free thiol‐containing peptide .…”

Thiopalmitoylated Peptides from the Peripheral Nervous System Myelin P0 Protein: Synthesis, Characterization, and Neuritogenic Properties

“…Our results show that the thiol protecting group had to be adjusted to the peptide sequence: Mmt was efficiently used for P0(180−199) thioacylation, but it was not suitable for thiopalmitoylation of P0(152−171) because of a premature deprotection of the Boc protecting group on the ε-NH 2 Lys in the presence of 2% TFA leading to dipalmitoylation. The deprotection of Lys170 ε-NH(Boc) in the presence of diluted TFA was quite unexpected, as in our previous work we obtained, using the same protocol for on-resin acylation, specific mono-palmitoylation of PLP(139−151) using Mmt protecting group for Cys140, even though this peptide possesses two lysines at residues 143 and 150 . It is interesting to note that P0(180−199) possesses a Lys residue at position 183 and no Boc deprotection was observed in the presence of 2%TFA.…”

“…Previously , we showed that the highly acid labile methoxytrityl (Mmt) group was the more versatile protecting group of the thiol for use in the on-resin synthesis of thiopalmitoylated PLP peptides, compared to the t -butylsulfenyl (StBu) protecting group . Here, however, we show that Mmt was not suitable for thiopalmitoylation of P0(152−171), because a side deprotection reaction occurred leading to dipalmitoylation.…”

Lipopeptide epitopes extended by an N ϵ ‐palmitoyl‐lysine moiety increase uptake and maturation of dendritic cells through a Toll‐like receptor‐2 pathway and trigger a Th1‐dependent protective immunity

“…The P 3 CSS moiety was then successfully introduced by Deres et al 22, by Defoort et al 23 and more recently by others 8, 11, and has played a role in attracting attention to the immunological properties of lipidated peptides without external immuno‐adjuvant (reviewed in 1). Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

“…Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

Synthesis of DNA‐Encoded Disulfide‐ and Thioether‐Cyclized Peptides

“…The Fmoc‐Cys(S‐ t Bu)‐OH is broadly used in solid‐phase peptide synthesis and has previously been applied to generate cysteine‐DNA conjugates in order to subsequently link DNA to proteins by expressed protein ligation . While the S‐ t Bu protecting group could efficiently be removed from the cysteine‐DNA conjugates, it has been reported in other studies that elimination of S‐ t Bu can require long reaction times of several hours . In a study by Halpin and co‐workers, Fmoc‐Cys(S‐ t Bu)‐OH was used to synthesize peptide–DNA conjugates on solid phase and they had reported problems to recover free thiol‐containing peptide .…”

Thiopalmitoylated Peptides from the Peripheral Nervous System Myelin P0 Protein: Synthesis, Characterization, and Neuritogenic Properties

“…Our results show that the thiol protecting group had to be adjusted to the peptide sequence: Mmt was efficiently used for P0(180−199) thioacylation, but it was not suitable for thiopalmitoylation of P0(152−171) because of a premature deprotection of the Boc protecting group on the ε-NH 2 Lys in the presence of 2% TFA leading to dipalmitoylation. The deprotection of Lys170 ε-NH(Boc) in the presence of diluted TFA was quite unexpected, as in our previous work we obtained, using the same protocol for on-resin acylation, specific mono-palmitoylation of PLP(139−151) using Mmt protecting group for Cys140, even though this peptide possesses two lysines at residues 143 and 150 . It is interesting to note that P0(180−199) possesses a Lys residue at position 183 and no Boc deprotection was observed in the presence of 2%TFA.…”

“…Previously , we showed that the highly acid labile methoxytrityl (Mmt) group was the more versatile protecting group of the thiol for use in the on-resin synthesis of thiopalmitoylated PLP peptides, compared to the t -butylsulfenyl (StBu) protecting group . Here, however, we show that Mmt was not suitable for thiopalmitoylation of P0(152−171), because a side deprotection reaction occurred leading to dipalmitoylation.…”

Lipopeptide epitopes extended by an N ϵ ‐palmitoyl‐lysine moiety increase uptake and maturation of dendritic cells through a Toll‐like receptor‐2 pathway and trigger a Th1‐dependent protective immunity

“…The P 3 CSS moiety was then successfully introduced by Deres et al 22, by Defoort et al 23 and more recently by others 8, 11, and has played a role in attracting attention to the immunological properties of lipidated peptides without external immuno‐adjuvant (reviewed in 1). Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

“…Association of peptide epitopes with dipalmitoyl‐thioester moiety using thiol‐protecting groups had also been reported 23, 24. Although these dipalmitoyl‐ and tripalmitoyl (P 3 CSS)‐lipidated “first‐generation lipopeptides” are highly immunogenic, they are relatively complex, difficult to assemble, tend to spontaneously form stable aggregates and vesicles, which considerably complicates their purification and their chemical and immunological characterization, and hinders eventual scale‐up pharmaceutical production 23, 24.…”

Synthesis of DNA‐Encoded Disulfide‐ and Thioether‐Cyclized Peptides

“…The Fmoc‐Cys(S‐ t Bu)‐OH is broadly used in solid‐phase peptide synthesis and has previously been applied to generate cysteine‐DNA conjugates in order to subsequently link DNA to proteins by expressed protein ligation . While the S‐ t Bu protecting group could efficiently be removed from the cysteine‐DNA conjugates, it has been reported in other studies that elimination of S‐ t Bu can require long reaction times of several hours . In a study by Halpin and co‐workers, Fmoc‐Cys(S‐ t Bu)‐OH was used to synthesize peptide–DNA conjugates on solid phase and they had reported problems to recover free thiol‐containing peptide .…”