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Muscle contraction

Muscle contraction. Structure of Thick Filament. Thick filaments consist of myosin molecules Myosin molecule built of 2 heavy (200000 Da) and 4 light (16000-25000 Da) chains Heavy chains are coiled around each other and form the “tail” of the molecule

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Muscle contraction

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  1. Muscle contraction

  2. Structure of Thick Filament • Thick filaments consist of myosin molecules • Myosin molecule built of 2 heavy (200000 Da) and 4 light (16000-25000 Da) chains • Heavy chains are coiled around each other and form the “tail” of the molecule • 2 light chains form the globular head of the molecule • The head has ATP-ase properties

  3. About 400 molecules of myosin are combined in the thick filament

  4. About half of molecules is directed to one end of filament, another half – to another end

  5. ÁÓÄÎÂÀ ТОНКОГО Ô²ËÀÌÅÍÒА Äî ñêëàäó òîíêèõ ô³ëàìåíò³â âõîäÿòü á³ëêè àêòèí, òðîïîì³îçèí ³ тðîïîí³í Дâ³ ôîðìè àêòèíó: ãëîáóëÿðíèé G-àêòèí ³ ô³áðèëÿðíèé F-àêòèí. Ìîëåêóëè ãëîáóëÿðíîãî àêòèíó íåêîâàëåíòíî ç‘єäíóþòüñÿ, óòâîðþþчèF-àêòèí. Äâà ëàíöþãè F-àêòèíó çàêðóчåí³ â ñï³ðàëü. Óæîëîáêóñï³ðàë³ F-àêòèíóðîçì³ùåíà òðîïîì³îçèíó. Ç îäí³єþ ìîëåêóëîþ òðîïîì³оçèíó êîíòàêòóþòü 7 ïàðàêòèíó. На 1 ìîëåêóëó тропоміозину припадає 1 молекула гëîáóëÿðíîãîá³ëêà òðîïîí³íó.

  6. Дâ³ ôîðìè àêòèíó: ãëîáóëÿðíèé G-àêòèí ³ ô³áðèëÿðíèéF-àêòèí. • Ìîëåêóëè ãëîáóëÿðíîãî àêòèíó íåêîâàëåíòíî ç‘єäíóþòüñÿ, óòâîðþþчèF-àêòèí. • Äâà ëàíöþãè F-àêòèíó çàêðóчåí³ â ñï³ðàëü. • Òðîïîí³íñêëàäàєòüñÿ ³ç 3-õ ñóáîäèíèöü (Ñ, ², Ò).

  7. ̳îô³áðèëè ì³ñòÿòü ïðèáëèçíî 2500 ô³ëàìåíò³â. Íà 1 òîâñòó ì³îçèíîâóíèòêó ïðèïàäàє6 òîíêèõ

  8. сòðóêòóðíа îäèíèöя ì³îô³áðèëè –ñàðêîìåð • îáèäâà ê³íö³òîâñòих ì³îçèíîâих íèòоê â³ëüí³ • òîíê³ íèòêè îäíèì ê³íöåì ïðèêð³ïëåí³ äîZ-ïëàñòèíîê

  9. ²îíè Ñà2+ ïðèєäíóþòüñÿ äî кàëüö³éçâ'ÿçóâàëüíî¿ñóáîäèíèö³ òðîïîí³íó òîíêèõ ô³ëàìåíò³â • Зì³íюється êîíôîðìàö³я á³ëêà. • Мîëåêóëа òðîïîì³îçèíó ïåðåì³ùується ïî æîëîáêó òîíêîãî ô³ëàìåíòà • В ðåçóëüòàò³ íà ìîëåêóëàõãëîáóëÿðíîãî àêòèíó â³äêðèâàþòüñÿ öåíòðè çâ'ÿçóâàííÿç ãîë³âêàìè ì³îçèíó

  10. ̳îçèíîâ³ ãîë³âêè ³ç çâ'ÿçàíèìèìîëåêóëàìè ÀÒÔ ïðèєäíóþòüñÿ äî íàéáëèæчèõ ìîëåêóë G-àêòèíó • ÀÒÔàçíèé öåíòð àêòèâóєòüñÿ, ã³äðîë³çóється ÀÒÔ • Гîë³âêа çãèíàється • Тîíêèé ô³ëàìåíò ïðîòÿãóється âçäîâæ ì³îçèíîâîãî • Нîâа ìîëåêóëа ÀÒÔ зâ'ÿçóється з ãîë³âêою ì³îçèíó • М³ñòок розривається • При наявності Са голівка зв’язується з наступною молекулою актину • Частота 50 разів/с • Голівки працюють не синхронно • Іìïóëüñèïåðåñòàþòü íàäõîäèòè • ÀÒÔàçà (êàëüö³єâà ïîìïà) ïåðåíîñèòü • Ñà2+ ³ç ñàðêîïëàçìè óöèñòåðíè • КîìïëåêñÑà2+-òðîïîí³í äèñîö³þє • Тðîïîì³îçèí çñóâàєòüñÿ • Бëîêóþться молекули актину • М³ñòêè ðîçðèâàþòüñÿ • Вîëîêíî ðîçñëàáëþєòüñÿ.

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