24 research outputs found

    A Systemic Functional Study of the Head Identification of the English Nominal Group

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    Head identification is the first and crucial step in describing and analyzing the English nominal group. The literature to date indicates that the way of identifying the Head of the English nominal group varies from one school of linguistics to another and even from one grammarian to another. This paper focuses on the English nominal group containing the word of and the research is conducted from the systemic functional linguistics perspective

    Chiral metallo-supramolecular complexes selectively recognize human telomeric G-quadruplex DNA

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    Here, we report the first example that one enantiomer of a supramolecular cylinder can selectively stabilize human telomeric G-quadruplex DNA. The P-enantiomer of this cylinder has a strong preference for G-quadruplex over duplex DNA and, in the presence of sodium, can convert G-quadruplexes from an antiparallel to a hybrid structure. The compound's chiral selectivity and its ability to discriminate quadruplex DNA have been studied by DNA melting, circular dichroism, gel electrophoresis, fluorescence spectroscopy and S1 nuclease cleavage. The chiral supramolecular complex has both small molecular chemical features and the large size of a zinc-finger-like DNA-binding motif. The complex is also convenient to synthesize and separate enantiomers. These results provide new insights into the development of chiral anticancer agents for targeting G-quadruplex DNA

    쀑ꡭ인 ν•œκ΅­μ–΄ ν•™μŠ΅μžλ₯Ό μœ„ν•œ μ™Έλž˜μ–΄ ꡐ윑 연ꡬ-쑰어법 ν™œμš©μ„ μ€‘μ‹¬μœΌλ‘œ-

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    ν•™μœ„λ…Όλ¬Έ (석사)-- μ„œμšΈλŒ€ν•™κ΅ λŒ€ν•™μ› : κ΅­μ–΄κ΅μœ‘κ³Ό, 2017. 2. ꡬ본관.μ™Έκ΅­μ–΄λ‘œ μ˜μ‚¬μ†Œν†΅μ„ ν•˜κΈ° μœ„ν•΄μ„œ λ°œμŒμ΄λ‚˜ 문법에 λŒ€ν•œ ν•™μŠ΅λΏλ§Œ μ•„λ‹ˆλΌ μ–΄νœ˜μ— λŒ€ν•œ ν•™μŠ΅μ΄ μ€‘μš”ν•˜λ‹€. μ–΄νœ˜λŠ” 어쒅에 따라 ν•œμžμ–΄, κ³ μœ μ–΄, μ™Έλž˜μ–΄μ˜ μ„Έ 가지 μ’…λ₯˜λ‘œ κ΅¬λΆ„λœλ‹€. ν•œκ΅­ μ‚¬νšŒμ˜ κΈ‰κ²©ν•œ κ΅­μ œν™”λŠ” μ–Έμ–΄ μ‚¬μš©μ—λ„ 큰 영ν–₯을 미치고 μžˆλŠ”λ° 특히 μ™Έλž˜μ–΄κ°€ μΌμƒμ—μ„œ μ°¨μ§€ν•˜λŠ” λΉ„μœ¨μ€ 높아지고 있으며, 이에 따라 ν•œκ΅­μ–΄ ν•™μŠ΅μžκ°€ μ™Έλž˜μ–΄λ₯Ό μ ‘ν•  κΈ°νšŒλ„ λ§Žμ•„μ§€κ³  μžˆλ‹€. 이 μ—°κ΅¬λŠ” 쀑ꡭ인 ν•œκ΅­μ–΄ ν•™μŠ΅μžλ“€μ˜ μ™Έλž˜μ–΄μ— λŒ€ν•œ 이해 λŠ₯λ ₯ 및 μ‚¬μš© λŠ₯λ ₯을 ν–₯μƒν•˜κ³ μž μ™Έλž˜μ–΄ ꡐ윑의 ν•„μš”μ„±μ„ ν”Όλ ₯ν•˜κ³ , 쑰어법 ν™œμš©μ„ μ€‘μ‹¬μœΌλ‘œ ν•˜λŠ” μ™Έλž˜μ–΄ ꡐ윑의 λ‚΄μš©κ³Ό λ°©μ•ˆμ„ λͺ¨μƒ‰ν•˜λŠ” 데에 κ·Έ λͺ©μ μ΄ μžˆλ‹€. ν•œκ΅­μ–΄μ—μ„œλŠ” μ™Έλž˜μ–΄ 음의 μŒμ ˆμ„ κ·ΈλŒ€λ‘œ ν‘œκΈ°ν•˜μ—¬ μ›μŒμ— κ°€κΉŒμš΄ λͺ¨μŠ΅μ„ μœ μ§€ν•˜κ³  μžˆλ‹€. λ°˜λ©΄μ—, μ€‘κ΅­μ–΄μ—μ„œλŠ” κ°•μ„Έκ°€ λ“€μ–΄μžˆλŠ” μ£Όμš” 음절만 ν‘œκΈ°ν•¨μœΌλ‘œμ¨ μŒμ ˆμ„ λŒ€ν­ μΆ•μ†Œν•˜λŠ” νŠΉμ§•μ„ 보이고 μžˆλ‹€. μ΄λŸ¬ν•œ 차이점으둜 μΈν•˜μ—¬ 쀑ꡭ인 ν•™μŠ΅μžκ°€ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄λ₯Ό μ΄ν•΄ν•˜λŠ” 데 어렀움이 μžˆλ‹€. 그리고 ν˜•νƒœμ μΈ μΈ‘λ©΄μ—μ„œ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄λŠ” νŒŒμƒ, ν•©μ„±, ν’ˆμ‚¬μ˜ 쀑볡, μƒλž΅, μ‹ μ‘°μ–΄ λ“± λ‹€μ–‘ν•œ ꡬ쑰 μœ ν˜•μ΄ 있기 λ•Œλ¬Έμ— ν•™μŠ΅μžκ°€ μ΄ν•΄ν•˜κΈ°μ— 어렀움이 λ”°λ₯Έλ‹€. 특히, 단일 μ™Έλž˜μ–΄λ³΄λ‹€ μ™Έλž˜μ–΄μ™€ λ‹€λ₯Έ μ–΄μ’…μ˜ λ‹¨μ–΄λ‚˜ 접사λ₯Ό κ²°ν•©ν•˜μ—¬ κ΅¬μ„±λœ ν•©μ„±μ–΄, νŒŒμƒμ–΄μ˜ ꡬ쑰가 더 λ³΅μž‘ν•˜κΈ° λ•Œλ¬Έμ— ν•œκ΅­μ–΄ 쑰어법에 λŒ€ν•œ 인식이 λΆ€μ‘±ν•˜λ©΄ μ™Έλž˜μ–΄ 의미λ₯Ό μ΄ν•΄ν•˜κΈ° μ–΄λ €μšΈ 것이닀. 이와 같은 λ¬Έμ œμ˜μ‹μ—μ„œ μΆœλ°œν•˜μ—¬ 이 μ—°κ΅¬μ—μ„œλŠ” 쀑ꡭ인 ν•™μŠ΅μžμ˜ μ™Έλž˜μ–΄ 이해 λŠ₯λ ₯을 ν–₯μƒν•˜κΈ° μœ„ν•΄ 효과적인 μ™Έλž˜μ–΄ ꡐ윑 λ‚΄μš©κ³Ό λ°©μ•ˆμ„ κ΅¬μ•ˆν•˜κ³ μž ν•˜μ˜€λ‹€. β…‘μž₯μ—μ„œλŠ” μ„ ν–‰ 연ꡬλ₯Ό ν† λŒ€λ‘œ λ¨Όμ € ν•œκ΅­μ–΄ μ™Έλž˜μ–΄μ˜ κ°œλ…κ³Ό μœ ν˜•μ— λŒ€ν•΄ μ‚΄νŽ΄λ³΄μ•˜λ‹€. κΈ°μ‘΄ μ—°κ΅¬μ˜ μ •μ˜μ™€ λΆ„λ₯˜ 기쀀을 μ •λ¦¬ν•˜μ—¬ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄μ˜ μ •μ˜λ₯Ό 내리고 쑰어법에 따라 μ™Έλž˜μ–΄λ₯Ό μœ ν˜•λ³„λ‘œ λΆ„λ₯˜ν•˜μ˜€λ‹€. 그리고 ν˜•νƒœμ  μΈ‘λ©΄μ—μ„œ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄λ₯Ό λŒ€μ‘° λΆ„μ„ν•˜μ˜€λ‹€. λ˜ν•œ μ€‘κ΅­μ—μ„œ 이루어지고 μžˆλŠ” ν•œκ΅­μ–΄ μ™Έλž˜μ–΄μ˜ ꡐ윑 ν˜„ν™©μ„ λΆ„μ„ν•˜μ˜€λ‹€. ꡐ윑 ν˜„ν™© 뢄석을 μœ„ν•΄ μ€‘κ΅­μ—μ„œ 좜판된 ν•œκ΅­μ–΄ ꡐ재λ₯Ό μ‚΄νŽ΄λ³΄κ³  ν•™μŠ΅μž 섀문을 μ‹€μ‹œν•˜μ˜€λ‹€. κ΅¬μ²΄μ μœΌλ‘œλŠ” 쀑ꡭ λ‚΄ λŒ€ν•™μ—μ„œ μ‚¬μš©ν•˜κ³  μžˆλŠ” ꡐ재λ₯Ό λΆ„μ„ν•˜μ—¬ κ΅μž¬μ—μ„œ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄λ₯Ό μ–΄λ–»κ²Œ μ œμ‹œν•˜κ³  μžˆλŠ”μ§€λ₯Ό κΈ°μˆ ν•˜μ˜€λ‹€. λ˜ν•œ 쀑ꡭ λŒ€ν•™μ— μž¬ν•™ 쀑인 쀑ꡭ인 ν•™μŠ΅μžμ—κ²Œ ꡐ수 ν•™μŠ΅ μ‹€νƒœ 쑰사λ₯Ό μ‹€μ‹œν•¨μœΌλ‘œμ¨ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ ν•™μŠ΅μ— λŒ€ν•œ νƒœλ„ 및 ν•™μŠ΅μ—μ˜ 어렀움 등을 μ‘°μ‚¬ν•˜μ˜€λ‹€. μ„€λ¬Έ 쑰사λ₯Ό ν† λŒ€λ‘œ 쀑ꡭ인 ν•™μŠ΅μžμ˜ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄μ— λŒ€ν•œ 이해 및 인식, ν•™μŠ΅ 경둜, μˆ˜μ—…μ—μ„œμ˜ ν•™μŠ΅ 방식 등에 λŒ€ν•˜μ—¬ λΆ„μ„ν•˜κ³  κ·Έ λ‚΄μš©μ„ μ œμ‹œν•˜μ˜€λ‹€. μ΄μ–΄μ„œ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ 사전 및 μ–΄νœ˜ 자료λ₯Ό λ°”νƒ•μœΌλ‘œ ν•œκ΅­μ–΄ ꡐ윑용 μ™Έλž˜μ–΄ λͺ©λ‘μ„ μ„ μ •ν•˜κ³  λ‚œμ΄λ„λ₯Ό μ œμ‹œν•˜μ˜€λ‹€. β…’μž₯μ—μ„œλŠ” μ„€λ¬Έ 쑰사와 인터뷰λ₯Ό ν†΅ν•˜μ—¬ 쀑ꡭ인 쀑급 ν•™μŠ΅μžμ˜ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ 이해 양상을 μ œμ‹œν•˜μ˜€λ‹€. 이λ₯Ό μœ„ν•˜μ—¬ λ¨Όμ € β…‘μž₯μ—μ„œ λ…Όμ˜ν•œ 이둠을 λ°”νƒ•μœΌλ‘œ 섀문지λ₯Ό μž‘μ„±ν•˜μ—¬ ν•™μŠ΅μžμ˜ μ™Έλž˜μ–΄ μ–΄νœ˜ 양적 λŠ₯λ ₯, 질적 λŠ₯λ ₯, 그리고 전체 이해 λŠ₯λ ₯을 μ‚΄νŽ΄λ³Έ ν›„, 였λ₯˜μ˜ 원인을 ꡬ체적으둜 νŒŒμ•…ν•˜κΈ° μœ„ν•΄ 사후 인터뷰λ₯Ό μ‹œν–‰ν•˜μ˜€λ‹€. 그리고 μˆ˜μ§‘λœ 자료의 κ²°κ³Όλ₯Ό λΆ„μ„ν•˜κΈ° μœ„ν•΄ 톡계 ν”„λ‘œκ·Έλž¨μ„ μ‚¬μš©ν•˜μ˜€λ‹€. β…£μž₯μ—μ„œλŠ” β…’μž₯μ—μ„œ μ‚΄νŽ΄λ³Έ κ²°κ³Όλ₯Ό λ°˜μ˜ν•˜μ—¬ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ ꡐ윑의 λͺ©μ  및 λͺ©ν‘œλ₯Ό μ œμ‹œν•˜μ˜€κ³  효과적인 μ™Έλž˜μ–΄ κ΅μˆ˜Β·ν•™μŠ΅ λ‚΄μš©μ„ κ΅¬μΆ•ν•˜μ˜€λ‹€. 이λ₯Ό μœ„ν•΄, 쑰어법(μ–΄κ·Ό, 접사 λ“± λ‹¨μœ„) 및 μ™Έλž˜μ–΄ μ‘°μ–΄ μœ ν˜•μ— λŒ€ν•œ 이해 ꡐ윑, 쑰어법 지식을 ν™œμš©ν•œ μ™Έλž˜μ–΄μ˜ ν˜•νƒœ νŠΉμ§•μ˜ 뢄석 ꡐ윑, 일뢀 μ™Έλž˜μ–΄ ν‘œκΈ°λ²•μ— λŒ€ν•œ κ°•μ‘° ꡐ윑, μ™Έλž˜μ–΄ μ˜λ―Έμ™€ μ˜μ–΄ 원어 및 쀑ꡭ어 μ™Έλž˜μ–΄ 의미의 비ꡐ μ„€λͺ… ꡐ윑, 그리고 의미망 ꡬ좕 및 μ–΄κ·Όμ΄λ‚˜ 접사 ν™œμš©μ„ ν†΅ν•œ μƒˆλ‘œμš΄ λ‹¨μ–΄μ˜ 생성 ꡐ윑 λ‚΄μš©μ„ κ΅¬μ•ˆν•˜μ˜€λ‹€. λ˜ν•œ μ‹€μ œ ꡐ윑 ν˜„μž₯μ—μ„œ μ μš©ν•  수 μžˆλ„λ‘ 탐ꡬ ν™œλ™μ„ μ€‘μ‹œν•˜λŠ” 'OHE(κ΄€μ°°-κ°€μ„€-μ‹€ν—˜)' λͺ¨ν˜•μ„ μ‚¬μš©ν•˜μ—¬ 쑰어법 ν™œμš©μ„ μ€‘μ‹¬μœΌλ‘œ ν•˜λŠ” μ™Έλž˜μ–΄ κ΅μˆ˜Β·ν•™μŠ΅ λͺ¨ν˜•κ³Ό ꡐ싀 ν™œλ™μ„ λ§ˆλ ¨ν•˜κ³  κ·Έ ꡐ윑적 효과λ₯Ό κ²€μ¦ν•˜μ˜€λ‹€. λ³Έ μ—°κ΅¬λŠ” 쀑ꡭ인 ν•™μŠ΅μžμ˜ μ™Έλž˜μ–΄ μ‘°μ–΄ μœ ν˜•μ„ λΆ„μ„ν•˜μ˜€λ‹€λŠ” 점과 쑰어법을 ν™œμš©ν•˜μ—¬ μ™Έλž˜μ–΄λ₯Ό μƒμ„±ν•˜κ±°λ‚˜ 의미λ₯Ό μœ μΆ”ν•˜μ˜€λ‹€λŠ” μ μ—μ„œ μ˜μ˜κ°€ μžˆλ‹€. μ•„μšΈλŸ¬ 쀑ꡭ인 ν•™μŠ΅μžλ“€μ΄ μ™Έλž˜μ–΄λ₯Ό μ‘°μ–΄ μœ ν˜•μ— 따라 λΆ„λ₯˜ν•˜κ³  μ‰½κ²Œ κΈ°μ–΅ν•  뿐 μ•„λ‹ˆλΌ μž₯기적으둜 κΈ°μ–΅ν•  수 있기 μœ„ν•˜μ—¬ 효과적인 μ™Έλž˜μ–΄ κ΅μˆ˜Β·ν•™μŠ΅ 방법을 λͺ¨μƒ‰ν–ˆλ‹€λŠ” μ μ—μ„œλ„ μ˜μ˜κ°€ μžˆλ‹€.β… . μ„œλ‘  1 1. μ—°κ΅¬μ˜ ν•„μš”μ„± 및 λͺ©μ  1 2. μ„ ν–‰ 연ꡬ 4 2.1. μ™Έλž˜μ–΄μ— λŒ€ν•œ ꡭ어학적 연ꡬ 4 2.2. μ™Έλž˜μ–΄μ— λŒ€ν•œ ν•œκ΅­μ–΄ κ΅μœ‘ν•™μ  연ꡬ 6 3. 연ꡬ λŒ€μƒ 및 연ꡬ 방법 7 β…‘. μ™Έλž˜μ–΄ ꡐ윑 연ꡬλ₯Ό μœ„ν•œ μ „μ œ 11 1. μ™Έλž˜μ–΄μ˜ κ°œλ…κ³Ό μœ ν˜• 11 1.1. μ™Έλž˜μ–΄μ˜ κ°œλ… 12 1.2. 쑰어법에 λ”°λ₯Έ μ™Έλž˜μ–΄μ˜ μœ ν˜• 20 2. ν•œκ΅­μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄μ˜ ν˜•νƒœμ  λŒ€μ‘° 뢄석 50 2.1. 원어 ν˜•νƒœμ˜ ν•œκ΅­μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄ 52 2.2. μ•½μ–΄ ν˜•νƒœμ˜ ν•œκ΅­μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄ 57 2.3. ν•©μ„± ν˜•νƒœμ˜ ν•œκ΅­μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄ 59 2.4. νŒŒμƒ ν˜•νƒœμ˜ ν•œκ΅­μ–΄μ™€ 쀑ꡭ어 μ™Έλž˜μ–΄ 62 3. 쀑ꡭ λ‚΄ ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ ꡐ윑 ν˜„ν™© 66 3.1. μ€‘κ΅­μ—μ„œ 좜판된 ν•œκ΅­μ–΄ ꡐ재 뢄석 66 3.2. μ™Έλž˜μ–΄ μˆ˜μ—…μ— λŒ€ν•œ ν•™μŠ΅μžμ˜ 인식 76 4. ν•œκ΅­μ–΄ ꡐ윑용 μ™Έλž˜μ–΄ λͺ©λ‘μ˜ μ„ μ • 79 4.1. ν•œκ΅­μ–΄ ꡐ윑용 μ™Έλž˜μ–΄ λͺ©λ‘ μ„ μ •μ˜ ν˜„ν™© 79 4.2. ν•œκ΅­μ–΄ ꡐ윑용 μ™Έλž˜μ–΄ λͺ©λ‘ μ œμ‹œ 및 λ‚œμ΄λ„ μ„€μ • 80 β…’. ν•™μŠ΅μžμ˜ μ™Έλž˜μ–΄ 이해 양상 및 였λ₯˜ 뢄석 88 1. 쑰사 방법 및 절차 88 1.1. 쑰사 μ°Έμ—¬μž 정보 88 1.2. 쑰사 방법 및 자료 ꡬ성 90 2. 쑰사 κ²°κ³Ό 및 뢄석 94 2.1. μ™Έλž˜μ–΄ 쑰어법에 λŒ€ν•œ 쑰사 κ²°κ³Ό 뢄석 94 2.2. μ™Έλž˜μ–΄ μ–΄νœ˜ 양적 λŠ₯λ ₯의 쑰사 κ²°κ³Ό 뢄석 97 2.3. μ™Έλž˜μ–΄ μ–΄νœ˜ λŠ₯λ ₯(양적&질적 λŠ₯λ ₯)의 쑰사 κ²°κ³Ό 뢄석 101 3. ν•™μŠ΅μžμ˜ 였λ₯˜ 원인 뢄석 113 3.1. λͺ¨κ΅­μ–΄μ™€ λͺ©ν‘œμ–΄μ˜ 단어 ꡬ쑰 차이λ₯Ό μΈμ‹ν•˜μ§€ λͺ»ν•œ 였λ₯˜ 113 3.2. 언어적 원인과 비언어적 원인 118 3.3. ν‘œκΈ°λ²•κ³Ό 쑰어법을 잘 μΈμ‹ν•˜μ§€ λͺ»ν•œ 였λ₯˜ 122 3.4. κ΅μœ‘κ³Όμ •μ˜ 영ν–₯에 μ˜ν•œ 였λ₯˜ 126 3.5. 기타 128 β…£. 쑰어법을 ν™œμš©ν•œ μ™Έλž˜μ–΄ ꡐ윑의 μ‹€μ œ 130 1. ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ ꡐ윑의 λͺ©μ κ³Ό λͺ©ν‘œ 130 2. ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ ꡐ윑의 λ‚΄μš© 132 2.1. 쑰어법 및 μ™Έλž˜μ–΄ μ‘°μ–΄ μœ ν˜•μ— λŒ€ν•œ 이해 136 2.2. 쑰어법 지식을 ν™œμš©ν•œ μ™Έλž˜μ–΄μ˜ ν˜•νƒœμ  νŠΉμ§• 뢄석 137 2.3. 일뢀 μ™Έλž˜μ–΄ ν‘œκΈ°λ²•μ— λŒ€ν•œ κ°•μ‘° 138 2.4. μ™Έλž˜μ–΄ μ˜λ―Έμ— λŒ€ν•΄ μ„€λͺ… 141 2.5. μƒˆλ‘œμš΄ λ‹¨μ–΄μ˜ 생성 144 3. ν•œκ΅­μ–΄ μ™Έλž˜μ–΄ κ΅μœ‘ν•™μŠ΅μ˜ 방법 145 3.1. 인식과 탐ꡬλ₯Ό ν†΅ν•œ ꡐ윑 방법 145 3.2. μ™Έλž˜μ–΄ μ–΄νœ˜μ§€λ„ μˆ˜μ—… λͺ¨ν˜• μ œμ‹œ 147 4. μ™Έλž˜μ–΄ κ΅μœ‘ν•™μŠ΅ 효과 검증 159 4.1. μ‹€ν—˜ λ‚΄μš© 및 μ°Έμ—¬μž μ„ μ • 160 4.2. μ‹€ν—˜ 도ꡬ 161 4.3. μ‹€ν—˜ κ²°κ³Ό 뢄석 164 β…€. κ²°λ‘  174 β€»μ°Έκ³ λ¬Έν—Œ 177 ※뢀둝 185 β€»ABSTRACT 197Maste

    Properties of the high‐spin heme of MauG are altered by binding of preMADH at the protein surface 40 Γ… away

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    The diheme enzyme MauG catalyzes oxidative post-translational modifications of a protein substrate, precursor protein of methylamine dehydrogenase (preMADH), that binds to the surface of MauG. The high-spin heme iron of MauG is located 40 Γ… from preMADH. The ferric heme is an equilibrium of five- and six-coordinate states. PreMADH binding increases the proportion of five-coordinate heme three-fold. On reaction of MauG with H2O2 both hemes become FeIV. In the absence of preMADH the hemes autoreduce to ferric in a multistep process involving multiple electron and proton transfers. Binding of preMADH in the absence of catalysis alters the mechanism of autoreduction of the ferryl heme. Thus, substrate binding alters the environment in the distal heme pocket of the high-spin heme over very long distance

    Properties Of The High-Spin Heme Of Maug Are Altered By Binding Of Premadh At The Protein Surface 40 Γ… Away

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    The diheme enzyme MauG catalyzes oxidative post-translational modifications of a protein substrate, precursor protein of methylamine dehydrogenase (preMADH), that binds to the surface of MauG. The high-spin heme iron of MauG is located 40 Γ… from preMADH. The ferric heme is an equilibrium of five- and six-coordinate states. PreMADH binding increases the proportion of five-coordinate heme three-fold. On reaction of MauG with H2O2 both hemes become FeIV. In the absence of preMADH the hemes autoreduce to ferric in a multistep process involving multiple electron and proton transfers. Binding of preMADH in the absence of catalysis alters the mechanism of autoreduction of the ferryl heme. Thus, substrate binding alters the environment in the distal heme pocket of the high-spin heme over very long distance

    A T67A Mutation In The Proximal Pocket Of The High-Spin Heme Of Maug Stabilizes Formation Of A Mixed-Valent Fe\u3csup\u3eIi\u3c/sup\u3e/Fe\u3csup\u3eIii\u3c/sup\u3e State And Enhances Charge Resonance Stabilization Of The Bis-Fe\u3csup\u3eIv\u3c/sup\u3e State

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    The diheme enzyme MauG catalyzes a six-electron oxidation required for posttranslational modification of a precursor of methylamine dehydrogenase (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. One heme is low-spin with ligands provided by His205 and Tyr294, and the other is high-spin with a ligand provided by His35. The side chain methyl groups of Thr67 and Leu70 are positioned at a distance of 3.4 Γ… on either side of His35, maintaining a hydrophobic environment in the proximal pocket of the high-spin heme and restricting the movement of this ligand. Mutation of Thr67 to Ala in the proximal pocket of the high-spin heme prevented reduction of the low-spin heme by dithionite, yielding a mixed-valent state. The mutation also enhanced the stabilization of the charge-resonance-transition of the high-valent bis-FeIV state that is generated by addition of H2O2. The rates of electron transfer from TTQ biosynthetic intermediates to the high-valent form of T67A MauG were similar to that of wild-type MauG. These results are compared to those previously reported for mutation of residues in the distal pocket of the high-spin heme that also affected the redox properties and charge resonance transition stabilization of the high-valent state of the hemes. However, given the position of residue 67, the structure of the variant protein and the physical nature of the T67A mutation, the basis for the effects of the T67A mutation must be different from those of the mutations of the residues in the distal heme pocket

    HYDROLOGICAL PROCESSES

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    Detecting water yield variability due to the small proportional land use and land cover changes in a watershed on the Loess Plateau, Chin
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