Biokimia Tumbuhan Hijau

• Main Author: Tan, Soon Chye (Author)
• Format: Book
• Language: Malay
• Published: Kuala Lumpur Dewan Bahasa dan Pustaka 1990
• Subjects: Plants; Botanical chemistry
• Online Access: Click Here to View Status and Holdings.

 It has long been known that the most common amino acid found in the N-terminal g of E. coli proteins is methionine (Waller, 1963). This suggests that methionine may be the first amino acid incorporated into nascent proteins. It is now clear that E. coli cells initiate protein synthesis by inserting N-for milmetionine (f-Met) using specific methionyl transfer RNA, i.e. f-met tRNA (initiator tRNA). This tRNA is a type of tRNA whose methionine has been formulated after binding to the tRNA. Non-terminal residues are incorporated into nascent proteins through tRNAs that receive different methionine, 3: Methionine tRNAs bound to these tRNAs cannot be formulated. The apparatus for protein synthesis is the ribosome. The ribosome contains two subunits, namely the large subunit and the small subunit. In E. coli, the molecular weight of the ribosome is approximately 2.5 million daltons. Its deposition coefficient is 70S, which consists of a large subunit (50S) and a small subunit (30S). The large subunit contains 35 proteins, 2 RNA molecules with deposition coefficients of 23S and 5S. while a small subunit (30S) A contains 21 proteins, 1 16S RNA molecule. Prokaryotes as well as mitochondria as well as chloroplasts, have ribosomes 70S, while eukaryotic cytoplasm contains ribos som 80S, which consists of large subunits (60S) and small subunits (40S). It is generally accepted that when proteins are synthesized in the ribosome (80S) of plant plasma cytos, the initiating tRNA is the tRNA that receives methionine, i.e. the unformilized methionine, while the formulated methionine is the initiating amino acid for protein synthesis occurring in the ribosome (70S) of chloroplasts.