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van der Wielen N, de Vries S, Gerrits WJ, Lammers-Jannink K, Moughan PJ, Mensink M, Hendriks W. Presence of Unabsorbed Free Amino Acids at the End of the Small Intestine Indicates the Potential for an Increase in Amino Acid Uptake in Humans and Pigs. J Nutr 2023; 153:673-682. [PMID: 36809852 DOI: 10.1016/j.tjnut.2023.01.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 01/29/2023] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND Unabsorbed free amino acids (AAs) at the end of the small intestine result in a potential preventable nutritional loss. OBJECTIVES This study aimed to quantify free AAs in terminal ileal digesta of both humans and pigs to investigate its relevance for the nutritional value of food proteins. METHODS Two studies with three diets were performed: a human study-ileal digesta from eight adult ileostomates were collected over 9 h after ingestion of a single meal unsupplemented or supplemented with 30 g zein or whey; pig study-12 cannulated pigs were fed for 7 d with a diet containing whey or zein or no-protein diet, and ileal digesta were collected on the last 2 d. Digesta were analyzed for total and 13 free AAs. True ileal digestibility (TID) of AAs was compared with and without free AAs. RESULTS All terminal ileal digesta samples contained free AAs. The TID of AAs in whey was 97% ± 2.4% (mean ± SD) in human ileostomates and 97% ± 1.9% in growing pigs. If the analyzed free AAs would have been absorbed, TID of whey would increase by 0.4%-units in humans and 0.1%-units in pigs. The TID of AAs in zein was 70% ± 16.4% in humans and 77% ± 20.6% in pigs and would increase by 2.3%-units and 3.5%-units, respectively, if the analyzed free AAs would have been fully absorbed. The largest difference was observed for threonine from zein: if free threonine was absorbed, the TID would increase by 6.6%-units in both species (P < 0.05). CONCLUSIONS Free AAs are present at the end of the small intestine and can potentially have a nutritionally relevant effect for poorly digestible protein sources, whereas the effect is negligible for highly digestible protein sources. This result provides insight into the room for improvement of a protein's nutritional value if all free AAs are to be absorbed. J Nutr 2023;xx:xx-xx. This trial was registered at clinicaltrials.gov as NCT04207372.
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Affiliation(s)
- Nikkie van der Wielen
- Animal Nutrition Group, Wageningen University and Research, Wageningen, the Netherlands; Division of Human Nutrition, Wageningen University and Research, Wageningen, the Netherlands.
| | - Sonja de Vries
- Animal Nutrition Group, Wageningen University and Research, Wageningen, the Netherlands
| | - Walter J Gerrits
- Animal Nutrition Group, Wageningen University and Research, Wageningen, the Netherlands
| | - Kim Lammers-Jannink
- Animal Nutrition Group, Wageningen University and Research, Wageningen, the Netherlands
| | - Paul J Moughan
- Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Marco Mensink
- Division of Human Nutrition, Wageningen University and Research, Wageningen, the Netherlands
| | - Wouter Hendriks
- Animal Nutrition Group, Wageningen University and Research, Wageningen, the Netherlands
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Identification of unexplored substrates of the serine protease, thrombin, using N-terminomics strategy. Int J Biol Macromol 2019; 144:449-459. [PMID: 31862363 DOI: 10.1016/j.ijbiomac.2019.12.137] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/15/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022]
Abstract
The function and regulation of thrombin is a complex as well as an intriguing aspect of evolution and has captured the interest of many investigators over the years. The reported substrates of thrombin are coagulation factors V, VIII, XI, XIII, protein C and fibrinogen. However, these may not be all the substrate of thrombin and therefore its functional role(s), may not have been completely comprehended. The purpose of our study was to identify hitherto unreported substrates of thrombin from human plasma using a N-terminomics protease substrate identification method. We identified 54 putative substrates of thrombin of which 12 are already known and 42 are being reported for the first time. Amongst the proteins identified, recombinant siglec-6 and purified serum alpha-1-acid glycoprotein were validated by cleavage with thrombin. We have discussed the probable relevance of siglec-6 cleavage by thrombin in human placenta mostly because an upregulation in the expression of siglec-6 and thrombin has been reported in the placenta of preeclampsia patients. We also speculate the role of alpha-1-acid glycoprotein cleavage by thrombin in the acute phase as alpha-1-acid glycoprotein is known to be an inhibitor of platelet aggregation whereas thrombin is known to trigger platelet aggregation.
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Sun M, Liang Y, Li Y, Yang K, Zhao B, Yuan H, Li X, Zhang X, Liang Z, Shan Y, Zhang L, Zhang Y. Comprehensive Analysis of Protein N-Terminome by Guanidination of Terminal Amines. Anal Chem 2019; 92:567-572. [DOI: 10.1021/acs.analchem.9b04141] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mingwei Sun
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, Guangdong 510005, China
| | - Yu Liang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Yang Li
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaiguang Yang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Baofeng Zhao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Huiming Yuan
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Xiao Li
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Xiaodan Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Zhen Liang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Yichu Shan
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Lihua Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
| | - Yukui Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning 116023, China
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