Labeled peptide
The most commonly encountered labeled
peptide are fluorophores and biotin tagged molecules. Depending on the position requirement for the
label (e.g. C-terminal, N-terminal) both label types can either be introduced
as prelabeled building blocks or through labeling reaction on completed peptide
chain. Genosphere Biotechnologies has
developed expertise in all labeling approaches to fulfill your
requirements. Labeled peptide are most
often tagged at the N-terminus or at the amino group of the Lysine side chain.
In addition, with suitably selected protecting groups a combined use of
different Lysine derivatives within the
peptide thus allowing multiple labeling sites per peptide.
Biotin labeled peptide
Biotin also called vitamin H is a small biologically active molecule
with a molecular weight of 244,31 Da. Biotin normally acts as a co-enzyme in
living cells. Biotin is widely used in life sciences to label biomolecules in
combination with the proteins avidin
from egg white or streptavidin from Streptomyces. They both exhibit a high binding affinity
towards biotin (KD: 10 - 15 mol/l).
Biotin-modified peptides are widely used in various assays. Genosphere Biotechnologies can synthesize
your Biotin labeled peptide with labeling on various site of the peptide
chain. Biotin may be linked on the
N-terminal alpha amine or the side chain epsilon-amine of a lysine at any
position on the peptide primary structure.
Cysteine thiol labeling is one other option for the introduction of a
biotin in the middle of the peptide sequence.
PEGylated Peptide
Genosphere Biotechnologies provides custom PEGylated
peptide production and PEGylation services for research peptides and
small molecules. PEGylation is the process of covalently attaching polyethylene
glycol (PEG) polymer chains to peptides. PEGylated peptide formation may be
achieved through an amide bond on the N-terminal a-amine of the a linear peptide or the side chain e-amine of a Lys included on C-terminal end of the target peptide
sequence for example. Other approaches
include covalent linkage to a Cys residue via a maleimide thiol reaction
intermediary.
The use of active peptide in in vivo experiments are sometimes limited
by either poor solubility, fast proteolytic degradation, or strong antigenic
response. By increasing their molecular
mass, PEGylated peptides shows enhanced pharmacokinetics properties. PEGylation has been shown to significantly
improve water solubility, biocompatibility, immunogenicity, and other
physico-chemical properties.
Indeed, the polyethylene glycol polymer
with the large amount of hydrogen bound water molecules, acts like a soft
shield protecting the attached peptide molecule from proteolytic enzymatic
degradation. Moreover, this hydrodynamic
bulky structure somewhat masks the potent immunogenic peptide epitopes from the
host’s immune system which in turns reduces immunogenicity and antigenicity and
thereby limiting adverse immunological effects. In addition it was established
that PEGylated peptides are more stable over a range of pH and temperature
changes when compared to the non-PEGylated peptide.
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