# Identification and Characterization of Fibronectin-Binding Peptides in Gelatin  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 12 School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China 2  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 12 School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China 2  
[PERSON]  
3 Library of Shandong Agricultural University, Tai'an 271018, China 3  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 1  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 1  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 1  
[PERSON]  
1 State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 12 School of Chemical and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China 2  
Footnote 1: [[https://www.mdpi.com/journal/polymers](https://www.mdpi.com/journal/polymers)]([https://www.mdpi.com/journal/polymers](https://www.mdpi.com/journal/polymers))  
Footnote 2: [[https://www.mdpi.com/journal/polymers](https://www.mdpi.com/journal/polymers)]([https://www.mdpi.com/journal/polymers](https://www.mdpi.com/journal/polymers))  
Footnote 3: [[https://www.mdpi.com/journals/20190](https://www.mdpi.com/journals/20190)]([https://www.mdpi.com/journals/20190](https://www.mdpi.com/journals/20190))  
hydroxylation modification of collagen. Hydroxyproline is a unique amino acid of collagen, and the content of hydroxproline differs with age and gender [10; 11]. Therefore, hydroxproline plays a critical role in collagen-FN binding. Due to the stronger binding activity of gelatin, undoubtedly, MW contributes to the binding because the modest MW radically exposed more FN-binding sites in denatured collagen than in collagen. However, these factors have yet to be thoroughly studied. In 1978, [PERSON] discovered \(\alpha\)1-CB7, digested by CNBr and purified by ion exchange chromatography, in residues 757-791, and the author identified this as the classic FN-binding region [12]. In [PERSON]'s study, FN could bind to collagen type I, II, III, IV, and V in vitro, as there is a binding site in every helix of collagen. Positions 643-819 in the \(\alpha\)1 chain contain an FN-binding site, and a domain homologous to the binding site in residues 693-1101 of the \(\alpha\)2 chain was identified by fluorescence chromatography [13]. [PERSON] separated two non-triple helical regions of collagen by FN-sepharose affinity chromatography, size exclusion high-performance liquid chromatography (HPLC), and enzyme-linked immunosorbent assay (ELISA) [14]. In addition, CNBr cleaved collagen \(\alpha\)1(II) to obtain CB10 (position 550-900), CB11 (100-400), CB8 (400-550), CB9.7 (900-1000), and CB12 (0-100). In these fragments, CB10 and CB12 had binding activity, as detected by fluorescence polarization, and the activity of CB8 was weaker. Furthermore, \(\alpha\)2(1)-CB4 and CB5, which were homologous to CB10 and CB12, respectively, were active in FN binding [15]. More recent research suggested that there were at least fourteen distinct sites in collagen type I to interact with FN: five on each of the \(\alpha\)1 chains and four on the \(\alpha\)2 chain, using fluorescence anisotropy [16]. However, all the above-mentioned studies used CNBr to cleave collagen and analyzed the binding activity of the cleaved fragments to FN, without specific binding site analysis. These fragments comprised a longer region, and the MW range was broad (from several thousand to tens of thousands).