碩士 / 國立清華大學 / 生命科學系 / 91 / Non-specific lipid transfer proteins (nsLTP)are involved in the movement of phospholipids, glycolipids, fatty acids and sterols between membranes. Plant ns-LTPs have been isolated from a number of plant species including maize, wheat, rice, barley and spainch. Rice ns-LTP1 is a basic protein, and its molecular mass is about 9 kDa. We determined the structure by X-ray crystallography and the crystal structure of rice ns-LTP1 and palmitic acid complex was determined at 2.1Å resolution. The crystal belonged to the orthorhombic crystal system and space group is C2221 with unit cell parameters a= 48.04 Å, b = 72.70 Å, c = 49.72 Å and α=β=γ=90°.Compared with the structure of unliganded rice nsLTP1, we found that helix3, residues Cys50 to Lys59, helix4, residues Ala66 to Ser71, and C-terminal loop, Lys72 to Ser91 had conformational changes. Then these cause the hydrophobic cavity larger and the palmitic acid inserted into cavity more easily. In the hydrophobic cavity of our liganded rice nsLTP1, we found two palmitic acids, and they are in head-to-tail. We think that the C-terminal loop of nsLTP1 is very flexible. When we increase the content of palmitic acid, C-terminal loop would swim away from the hydrophobic cavity and the second palmitic acid would inserted into the cavity. Compared to other plant nsLTP1s, we found that Tyr79 and Ile81 display important roles. Their conformational changes of side-chain are the factors that the second palmitic acid could insert into the cavity.
| Identifer | oai:union.ndltd.org:TW/091NTHU0105046 |
| Date | January 2003 |
| Creators | Cheng, Pei-tsung, 鄭培聰 |
| Contributors | Yuh-Ju Sun, 孫玉珠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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