"ANP FAP and aP NIRF were synthesized by CPC Scientific (Sunnyvale, CA)… Another internally-quenched FRET peptide substrate (ANPFAP) for FAP has recently been reported and demonstrated for use as an activity-based, in vivo imaging tool. The peptide sequence contains two internal Gly-Pro dipeptide motifs, susceptible to FAP cleavage and a Cy5.5/QSY21, quenched-FRET pair."
Abstract
Fibroblast Activation Protein (FAP) is a membrane-bound serine protease whose expression is often elevated in activated fibroblasts associated with tissue remodeling in various common diseases such as cancer, arthritis and fibrosis. Like the closely related dipeptidyl peptidase DPPIV, the extracellular domain of FAP can be released into circulation as a functional enzyme, and limited studies suggest that the circulating level of FAP correlates with the degree of tissue fibrosis. Here we describe a novel homogeneous fluorescence intensity assay for circulating FAP activity based on a recently identified natural substrate, FGF21. This assay is unique in that it can effectively distinguish endopeptidase activity of FAP from that of other related enzymes such as prolyl endopeptidase (PREP) and was validated using Fap-deficient mice. Structural modeling was used to elucidate the mechanistic basis for the observed specificity in substrate recognition by FAP, but not by DPPIV or PREP. Finally, the assay was used to detect elevated FAP activity in human patients diagnosed with liver cirrhosis and to determine the effectiveness of a chemical inhibitor for FAP in mice. We propose that the assay presented here could thus be utilized for diagnosis of FAP-related pathologies and for the therapeutic development of FAP inhibitors.
SOCIAL MEDIA
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Baba, Osamu, Andrew Elvington, Martyna Szpakowska, Deborah Sultan, Gyu Seong Heo, Xiaohui Zhang, Hannah Luehmann et al. bioRxiv (2020).
The FC131 peptide (cyclo[2-Nal-Gly-d-Tyr-NMe-d-Orn-Arg]) was synthesized by CPC Scientific (Sunnyvale, CA).
This guide will help you understand how to read ESI spectra for large and complex bio-molecules like peptides. Other techniques such as high-performance liquid chromatography (HPLC) show one major peak (i.e., absorbance and purity for RP-HPLC) in the spectra, making the interpretation straightforward. ESI-MS spectra are more complicated due to the multiplicity of the data. While most small molecules (100-500 AMU) behave well in ESI-MS and ionize as a single charged state, larger biomolecules, such as peptides, ionize as multiple charged variants. A major advantage of ESI-MS over other mass spectroscopy techniques is that molecular fragmentation is rare (t-Boc groups and a few other protection groups are an exception), which is why ESI-MS is often referred to as a soft ionization technique.
Vickers, Timothy A., Meghdad Rahdar, Thazha P. Prakash, and Stanley T. Crooke. Nucleic Acids Research (2019).
A solution of 1.5 umol SmBiT peptide (Val-Thr-Gly-Tyr-Arg-Leu-Phe-Glu-Glu-Ile-Leu-Gly-Gly-Ser-Gly-Gly-Lys(N3)-NH2) containing an azide group at the C-terminus (CPC Scientific, 1245 Reamwood Ave, Sunnyvale, CA, USA) in DMSO (0.5 ml) was added and the reaction mixture was stirred at room temperature for 5 h.
Solid-phase peptide synthesis (SPPS) has many advantages over liquid-phase peptide synthesis (LPPS) for preparing and manufacturing synthetic peptides. Except the synthesis of short peptide sequences (i.e., less than five amino acid residues), SPPS is faster, more efficient, and more economical than liquid-phase peptide synthesis (LPPS). Some of the advantages of SPPS include: (1) Excess reagents and products can be easily washed away, (2) using excess reagents to increase reaction rates and drive reactions to completion, (3) intermediates do not require isolation or characterization, (4) access to a broader range of solvents with low volatility and high polarity, (5) tethered peptide provides a ‘pseudo-dilute’ microenvironment, which can inhibit intermolecular reactions, making some modifications easier to accomplish, and (6) compatibility with automated synthesis technology.
Lo, J.H., Hao, L., Muzumdar, M.D., Raghavan, S., Kwon, E.J., Pulver, E.M., Hsu, F., Aguirre, A.J., Wolpin, B.M., Fuchs, C.S. and Hahn, W.C. Molecular Cancer Therapeutics 17, no. 11 (2018): 2377-2388.
pTP-TAMRA-iRGD (CH3(CH)15-[GWTLNSAGYLLGKINLKALAALAKKIL-GGK(TAMRA)GGCRGDKGPDC, Cys-Cys bridge]) used in all figures except Fig. S1 was synthesized by CPC Scientific.
Ng, Ee Xien, Myat Noe Hsu, Guoyun Sun, and Chia-Hung Chen. Methods in Enzymology 628 (2019): 59-94.
The peptide sequences of the four FRET-based substrates ([..] CPC Scientific) are as follows: UV: AlexaFluor405-Leu-Ala-Gln-Ala-HompheArg-Ser-Lys (QSY35)-NH2; Blue: Dabcyl-Gly-Pro-Leu-Gly-Met-Arg-Gly-Lys (5-FAM)-NH2; Green: QSY7-Ala-Pro-Phe-Glu..
West, J.A., Tsakmaki, A., Huang, J.H., Ghosh, S.S., Parkes, D.G., Wismann, P., Rigbolt, K.T., Pedersen, P.J., Pavlidis, P., Maggs, D. and Lopez-Talavera, J.C. bioRxiv (2019) 822122.
- Fractyl Laboratories Inc, Lexington, MA, 02421, USA
- Diabetes Research Group, School of Life Course Sciences, Faculty of Life Science and Medicine, King’s College London, London, WC2R 2LS, England, UK
[..] infusion of vehicle 2 via osmotic minipump; (2) glucagon-like peptide-1 receptor (GLP-1R) agonist (0.2 mg/kg liraglutide, SC, QD, Victoza (Novo Nordisk, Bagsværd, Denmark) and continuous infusion of vehicle 2 via osmotic minipump; (3) vehicle 1 (SC, QD) and continuous infusion of a glucose-dependent insulinotropic polypeptide receptor (GIPR) antagonist (∼4.5 mg/kg/day / 56.8 nmol/kg/h GIP[3-30]NH2, CPC Scientific Inc, Sunnyvale, CA, USA) via osmotic minipump;
Artur Javmen, Vladimir Y. Toshchakov, et al. Journal of Leukocyte Biology (2019).
All CPDPs included the N‐terminal Antennapedia homeodomain sequence RQIKIWFQNRRMKWKK.38 The Cy3‐labeled peptides were produced by CPC Scientific (Sunnyvale, CA, USA). The Cy3 label was placed at the peptide N‐terminus..
Gilles, Maud-Emmanuelle, Slack, Frank J, et al. Oncotarget, 2019, Vol. 10, (No. 51), pp: 5349-5358
"Tandem peptide (pTP-iRGD: CH3(CH)15-GWTLNSAGYLLGKINLKALAALAKKIL-GGK(TAMRA)GGCRGDKGPDC, Cys-Cys bridge) was synthesized by CPC Scientific."
