Leucine Leu

Evidence soon emerged that the endogenous opioids were peptides rather than simple morphine-like molecules (9). The first direct evidence for endogenous opioids in brain extracts was provided in 1975 when two pentapeptides were purified that differed only in the carboxyl terminal amino acids (10) (Table 1). These peptides were called methionine- (Met-) and leucine- (Leu-) enkephalin, from the Greek term meaning "in the head."... 

It is a peptide containing 27 amino acid residues containing the amino acids L-histidine (His) L-aspartic acid (Asp) L-serine (Ser) glycine (Gly) L-threonine (Thr) L-phenyl-alanine (Phe) L-glutamic acid (Glu) L-glutamine [Glu(NHj)] L-leucine (Leu) L-arginine (Arg) L-alanine (Ala) and L-valinamide (Va -NHj). 

Ferritin is a globular iron-storage protein that stores iron as FeJ+. To leave the ferritin, Fe3+ must first be reduced to Fe2+. Ferritin has two types of channels through which the Fe"+ could leave a three-fold channel and a four-fold channel. The three-fold channel is lined with the amino acids aspartate (Asp) and glutamate (Glu) and the four-fold channel is lined with the amino acid leucine (Leu). Through which channel is the Fe + more likely to leave the ferritin protein Explain your answer. 

Leucine (Leu or L) ((A)-2-amino-4-methyl-pentanoic acid) is a neutral, aliphatic amino acid with the formula HOOCCH(NH2)CH2CH(CH3)2 and with a hydrocarbon side chain. Leu is classified as a hydrophobic (nonpolar) amino acid. ... 

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