Poly -sarcosine

PolyDOX Doxorubicin-loaded hyaluronan-h/oc -poly( y-benzyl glutamate) vesicle PSar Poly(sarcosine)... 

Fig. 12 (a) Chemical structure of poly(sarcosine)-b-poly(y-methyl L-glutamate) copolymer. 

Few experimental data are available for establishing the existence of Poisson distributions in poly a-amino acids prepared in this way. Fessler and Ogston [26] showed from sedimentation measurements that poly-sarcosine samples had sharp distributions which could be Poissonian, and Pope et al. [27], employing column fractionation, demonstrated a Poisson... 

As shown in Table 9 acetylation of polysarcosine destroys the effect and the addition of such a polymer to phenylalanine dimethyl amide only slightly accelerates the process. (5) No effect is observed when sarcosine NCA is block-polymerised in poly-D.L-phenylalanine. 

Copolymers of L-proline and sarcosine have been prepared by Fasman and Blout (1961). These were found to exist in two forms, analogous to poly-L-proline. Form I, which is obtained directly from the copolymerization mixture showed anomalous optical rotatory dispersion and relatively low viscosity. On dissolving form I in 2-chloroethanol, form II is obtained which exhibits normal optical rotatory dispersion and relatively high viscosity. Fasman and Blout have suggested that the transition, form I —> form II, involves a conversion of the structure from ds- amide bonds to fmns-amide bonds. 

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

More recently Ballard [73] has reported that poly-L-proline does not show the chain-effect with DL-phenylalanine NCA. He has also studied a number of block copolymers of L-proline and sarcosine as initiators with results shown in Table 5. The complex behaviour observed is discussed by Ballard in terms of availability to peptide sites for NCA adsorption. It is concluded that poly-L-proline does not adsorb the NCA. The existence of a chain effect with the initiators (Sarc)j o(Pro), qX and (Sarc)5 (Pro), qX requires explanation it may be connected with the occurrence of conformations of the proline chain in which the terminal base group X is not far removed from the sarcosine tail . 

Polymerization of DL-phenylalanine NCA. Initiation by poly-L-proline and block copolymers of L-proline and sarcosine. (Nitrobenzene solution at 25°C. [NCAJo =0.1 mole r )... 

Another type of polypeptide-containing block copolymer, amphiliphilic rod-coil diblock copolymers such as poly (/V-triflu-oroacetyl-L-lysine)-/>-sarcosine) (Kt - Sa), were also synthesized and characterized by Gallot and coworkers [47]. The hydrophobic rod block poly(A-trifluoroacetyl-L-ly-sine) (Kt) was prepared by polymerization of Kt-NCA using A-hexylamine as the initiator. After fractionation using DMF (good solvent)/water (nonsolvent), the narrowly dispersed polymer (Kt) was then used as macroinitiator to initiate polymerization of the second monomer (Sa-NCA) to afford the hydrophilic block. Final elimination of Kt and Sa homopolymers were performed by precipitation with acetone and water respectively. The synthesis of Kt-Sa diblock copolymer is shown in Scheme 3. 

Figure 3. Deprotection peak heights as a function of host residue (-X-X-) and chain length in the SPPS of the known difficult peptide test sequence H- Ala) -X-X-(Ala)3-Val-poly-dimethylacrYlamide (I). (a) General hydrophobic residues, (b) Eff of side-chain protection of cysteine, (c) Effect of trityl protection of side-chain carboxamide of glutamine and asparagine, (d) Effect of arginine and tertiary amino acids proline and sarcosine. (Reproduced from ref. 51 with permission from Munksgaard International Publishers Ltd., Copenhagen.)...

Other organic compovmds that have been determined in sewage effluents by gas chromatography-mass spectrometry include the following (Table 16.7) nanylphenoxycarboxylic adds, chlorinated hydrocarbons, poly-chlorobiphenyls, organochlorine insectiddes, hexachlorophene, penta-chlorophenol, N-(phenylsulphonyl) sarcosine, dimethyl di, tri and tetrasulphides, Abrazine, Nirex, and volatile organic compoimds. 

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