グリシンは,過飽和水溶液で主にジマーではなくモノマーとして存在します:その結晶化と多形性を理解するための意味合い
Jun Huang1, Thomas C Stringfellow, Lian Yu
1School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA.
Journal of the American Chemical Society
|September 26, 2008
まとめ
グライシンは二酸化物ではなくモノマーとして,過飽和溶液に存在し,結晶化行動に関する以前の仮定に異議を唱える. この発見は,アミノ酸の自己結合と多形化に関する私たちの理解に影響を与えます.
科学分野:
- 物理化学 物理化学
- クリスタルグラフィーです.
- バイオフィジックス 生物物理学
背景:
- 最も単純なアミノ酸であるグリシンは,以前,過飽和溶液でダイマーを形成し,特定のポリモルフ (アルファ) に結晶化することを影響すると考えられていた.
- この自己結合は,解の行動と多形選択性を結びつける一般的な原理と考えられた.
研究 の 目的:
- 超飽和水溶液中のグリシンの溶液状態を調査する.
- グライシンがモノマーまたはジマーとして存在するかどうかを判断し,潜在的なジマーの安定性を評価する.
- 前述のジメリゼーションの証拠として引用されたグリシン拡散に対する老化効果を再評価する.
主な方法:
- 凍結点低気圧測定では,30%までの超飽和度.
- パルスグラデーションスピンエコー核磁気共鳴 (NMR) スペクトロスコーピーは,拡散を測定する.
- 拡散性および粘度データに適用されたストークス-アインシュタイン関係.
主要な成果:
- グリシンは,過飽和溶液中の単体として主に存在し,二元体の安定常数 (K D) は0.1kg H2O/mol未満です.
- 5日間の24%の超飽和まで,グリシン拡散に対する老化効果は観察されなかった.
- 計算された溶液の大きさは,濃度や溶液の年齢によって増加せず,モノメリックな振る舞いを示した.
結論:
- グリシンは主に過飽和水溶液のモノマーとして存在し,二分化に関連した老化効果を示さない.
- この発見は,アルファ-グリシンが通常の条件下で好ましいポリモルフであるという仮定の再評価を必要とします.
- この研究は,グリシンに対する多形選択性を決定する自己結合の提案された一般原則に異議を唱える.
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