Review

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«“√ “√«‘∑¬“»“ µ√å ¡¢. ªï∑’Ë 39 ©∫—∫∑’Ë 1 45
®“°¢âÕ¡Ÿ≈Õߧåª√–°Õ∫¢Õß S-layer cell wall
· ¥ß„Àâ∑√“∫«à“ S-layer ¢ÕßÕ“√凧’¬Õ∫‡§Á¡
¡’ª√‘¡“≥°√¥Õ–¡‘‚π∑’Ë¡’À¡Ÿàøíß°å—π‡ªìπ≈∫ª√‘¡“≥¡“°
¥—ßπ—Èπ‡¡◊ËÕÕ¬Ÿà„π ¿“«–∑’Ë¡’‡°≈◊Õ Ÿß‚§√ß √â“ߢÕß
‚ª√µ’π®–Õ¬Ÿà„π‚§√ß√Ÿª∑’ˇÀ¡“– ¡ ‰¡à‡°‘¥°“√º≈—°
°—π√–À«à“ߪ√–®ÿ≈∫∑’Ë¡’¡“° (repulsive interaction)
‡π◊ËÕß®“°¡’ª√–®ÿ∫«°Àπ÷ËߢÕß‚´‡¥’¬¡‰ÕÕπ (Na + ) ·≈–
ª√–®ÿ Õß∫«°¢Õß·¡°π’‡´’¬¡‰ÕÕÕπ (Mg 2+ ) ‡¢â“‰ª
‡°‘¥æ—π∏–‰ÕÕÕππ‘° ‡√’¬°ª√“°Ø°“√≥åπ’È«à“ Shielding
of negative charge by cation ·µà‡¡◊ËÕÕ¬Ÿà ¿“«–∑’Ë¡’‡°≈◊Õ
µË” ®–‡°‘¥°“√º≈—°°“√√–À«à“ߪ√–®ÿ≈∫‡π◊ËÕß®“°‰¡à¡’
ª√–®ÿ∫«°¢Õß‚´‡¥’¬¡‰ÕÕÕπ‰ª‡°‘¥æ—π∏–‰ÕÕÕπ‘°
°—∫À¡Ÿàøíß°å—π‡ªìπ≈∫¢Õß°√¥Õ–¡‘‚π∑’˺π—߇´≈≈å ´÷Ëß
‡ªìπªí®®—¬À≈—°∑’Ë∑”„À₧√ß √â“ߢÕß‚ª√µ’π‰¡àÕ¬Ÿà„π
‚§√ß√Ÿª∑’ˇÀ¡“– ¡ (unfolding) ·≈–‰¡à¡’§«“¡‡ ∂’¬√
(destabilization) ∑”„À₧√ß √â“ߢÕߺπ—߇´≈≈剡à
·¢Áß·√ß ®÷ß∑”„Àâ‰¡à “√∂∑πµàÕ°“√‡ª≈’ˬπ·ª≈ß
§«“¡¥—πÕÕ ‚¡µ‘°¿“¬‡´≈≈å ∑’ˇ°‘¥®“°°“√ª√—∫ ¡¥ÿ≈
(osmotic balance) √–À«à“ß¿“¬„π°—∫¿“¬πÕ° ∑”„Àâ
‡°‘¥°“√‰À≈¢ÕßπÈ”‡¢â“ Ÿà‡´≈≈å¿“¬πÕ°‡´≈≈åµ≈Õ¥‡«≈“
àߺ≈„Àâ„À⇴≈≈å§àÕ¬Ê ‡ª≈’ˬπ√Ÿª√à“ß®“°·∑à߉ª‡ªìπ
°≈¡ ·≈–·µ°ÕÕ°„π∑’Ë ÿ¥
(a)
√Ÿª∑’Ë 5 · ¥ß Transmission Electron micrographs of Halococcus salifodinae (a) and Halobacterium
salinarum (b) (∑’Ë¡“: Oren, 2006)
(b)
®“°√Ÿª∑’Ë 5a · ¥ß„Àâ‡ÀÁπ«à“ºπ—߇´≈≈å¢Õß
Õ“√凧’¬Õ∫‡§Á¡∑’Ë¡’√Ÿª√à“ß°≈¡ ‰¡à¡’‚ª√µ’π‡ªìπ
Õߧåª√–°Õ∫·≈–¡’§«“¡Àπ“¡“°°«à“Õ“√凧’¬Õ∫‡§Á¡
√Ÿª√à“߉¡à°≈¡ ‡àπ ºπ—߇´≈≈å¢Õß Halococcus ‡√’¬°
«à“ Thick sulfated heteropolysaccharide cell wall
´÷ËßÕߧåª√–°Õ∫ºπ—߇´≈≈å®–§≈⓬°—∫ Murein
¢Õß·∫§∑’‡√’¬ ‡√’¬°«à“ Pseudomurein à«π∑’Ë·µ°µà“ß
§◊Õ ®–æ∫ Gal =galactose; GalNAc =
N-cetylgalactosamine; Glc = glucose, Gly = glycine;
GulNUA = N acetylgulosaminuronic acid; Man =
mannose; UA = uronic ”À√—∫ °ÿ≈ Natronococcus
®–¡’ºπ—߇´≈≈å∑’ËÀπ“‡àπ°—π·µà¡’Õߧåª√–°Õ∫·µ°µà“ß
®“° °ÿ≈ Halococcus ‚¥¬¡’‚¡‚π‡¡Õ√凪ìπ poly
(L-glutamine) glycoconjugate ¥—ßπ—Èπºπ—߇´≈≈套߰≈à“«
‰¡à¡’‚ª√µ’π‡ªìπÕߧåª√–°Õ∫ ·≈–¡’§«“¡Àπ“ ®÷ß∑”
Àπâ“∑’Ë√—°…“√Ÿª√à“ß∑’Ë·∑â®√‘ߢÕßÕ“√凧’¬Õ∫‡§Á¡√Ÿª√à“ß
°≈¡ ‰¡à«à“®–Õ¬Ÿà„π ¿“«–∑’ˇªìπ Hypotonic À√◊Õ
Hypertonic (Schleifer et al., 1982) ‡π◊ËÕß®“°Õ“√凧’¬
Õ∫‡§Á¡∑’Ë “¡“√∂º≈‘µ¿—≥±å∑“ßÕÿµ “À°√√¡¡’
√Ÿª√à“ß·∑àß (Halobacterium) ·≈–√Ÿª√à“߉¡à·πàπÕπ