8-Arm PEG-GAA is a multiarmed PEG derivative with carboxylic acid at each terminal of the eight arms connected to one hexaglycerol core. GAA stands for the glutaramide acid. There is a C4 amide linkage between PEG and COOH. PEG acid can be used to react with amine groups with peptide coupling reagents.
Difference among all the PEG acid we offer:
Type A: AA
Methylene (CH2) linkage between PEG and acid (COOH)
Type B: GA
C4 aliphatic ester linkage between PEG and acid (COOH)
Type C: SA
C3 aliphatic ester linkage between PEG and acid (COOH)
Type D: GAA
C4 aliphatic amide linkage between PEG and acid (COOH)
Type E: SAA
C3 aliphatic amide linkage between PEG and acid (COOH)
AA: Acetic Acid, also called CM - Carboxyl Methyl; GA: Glutaric Acid; SA: Succinic Acid; GAA: GlutarAmide Acid; SAS: SuccinAmide Acid
Molecular weight: 8-Arm PEG MW refers to the MW of the entire PEG molecule. The MW of each arm is 1/8 of the MW indicated in the product name. MW of PEG was measured by MALDI-MS or GPC. PDI (polydispersity index) of our 8-Arm PEG is 1.02-1.06 with very narrow MW distribution. The number of repeating ethylene oxide units (CH2CH2O) or the degree of polymerization is calculated dividing the PEG MW by 44 (44 is the molecular mass of one repeating unit).
Solubility: Soluble in water and aqueous buffer, chloroform, methylene chloride, DMF, DMSO, and less soluble in alcohol, toluene. Not soluble in ether.
Density: PEG density is approximately 1.125 g/mL
Physical form: PEG products generally appear as white or off-white powder, and for certain special 8-arm PEGs, it may appear as wax-like, semi-solid material due to low MW and the type of functional groups.
Storage condition: PEG product shall be stored in the original form as received in a freezer at -20C or lower for long term storage. Stock solution of PEG reagents that do not contain oxygen or moisture sensitive functional groups may be temporarily stored in a refrigerator or ambient temperature for multiple days. Stock solution should avoid repeated freeze-and-thaw cycles. See Documents section for detailed storage and handling conditions.
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