Pathway maps

Saturated fatty acid biosynthesis
Saturated fatty acid biosynthesis

Object List (links open in MetaCore):

Crotonyl-ACP,, D-beta-Hydroxy- butyryl-ACP, Butyryl-ACP,, 3-Oxododecanoyl-ACP,, 3-Oxo-hexadeca- noyl-ACP, (E)-Dec-2-enoyl-ACP, Decanoyl-ACP, (R)-3-Hydroxy- hexa-decanoyl-ACP,,, (E)-Hexadec-2- enoyl-ACP,,, Acetoacyl-ACP,,, (R)-3-Hydroxy- hexanoyl-ACP, (E)-Hex-2-enoyl-ACP,,,,, 3-Oxo-tetradecanoyl-ACP, (R)-3-Hydroxy- tetradecanoyl-ACP,, (E)-Tetradec-2-enoyl-ACP,, Tetradeca- noyl-ACP,, 3-Oxohexanoyl-ACP,,,,, (R)-3-Hydroxy -octanoyl-ACP, 3-Oxooctonoyl-ACP, Hexanoyl-Acp,,, ACACB, Dodecanoyl-ACP, ACACA, (E)-Dodec-2- enoyl-ACP, (R)-3-Hydroxy- dodecanoyl-ACP,,, Malonyl-ACP,, Malonyl CoA,,, 3-Oxocaproyl-ACP, (R)-3-Hydroxy- decanoyl-ACP,,, Octanoyl-Acp, Palmitic acid, FASN,,, Hexadeca- noyl-ACP,, (E)-Oct-2-enoyl-ACP,, Acetyl-CoA, Acetyl-ACP


Saturated fatty acid biosynthesis.

Saturated fatty acids play an important role in the organism. They are essential for growth and development of the body and for normal functioning of many systems, in prevention of atherosclerosis, regulation of the blood pressure, muscles activity and enzymes. The lack of any of saturated fatty acid causes multiple diseases.

The first reaction in the biosynthesis of saturated fatty acids is carboxylation of Acetyl-CoA to form Malonyl-CoA. This reaction takes place in the presence of two enzymes, Acetyl-Coenzyme A carboxylase alpha 1 ( ACACA ) [1], [2], [3], [4], [5], [6], [7] and Acetyl-Coenzyme A carboxylase beta ( ACACB ), [1], [2], [8], [9], [4], [10], [6].

Malonyl-CoA forms complex with acyl-carrier protein Malonyl-ACP as the result of reaction catalyzed by fatty acid synthase ( FASN ) [11], [12], [13], [14], [15]. FASN is a multifunctional protein that has 7 catalytic activities. FASN complex consists of the enzymes cound to the acyl carrier protein. Acetyl-ACP is formed by condensation of Acyl-carrier protein and Acetyl-CoA catalyzed by FASN [11], [12], [13], [14], [16], [15], [17]. Acetoacetyl -ACP is then synthesized from Acetyl-ACP and Malonyl-ACP in the reaction also catalyzed by FASN complex [14], [12], [13], [14], [16], [15], [18], [17]. The three recurring reactions then take place. The first reaction is the reduction of keto group of Acetoacetyl-ACP to alcohol group of D-beta-Hydroxybutyryl-ACP. The second reaction is the dehydratation of D-beta-Hydroxybutyryl-ACP resulting in formation of Crotonyl-ACP. The third reaction is a reduction of double bond in Crotonyl-ACP resulting in formation of Butyryl-ACP [11], [12], [13], [14], [15], [17].

The above 3 reactions continue in a cycle. With each new turn of the cycle FASN catalyzes attachment of a compound formed in the previous cycle to the Malonyl-ACP complex. This results in elongation of the saturated fatty acid chain by two carbon atoms. For example, Butyryl-ACP from the first cycle will react with Malonyl-ACP to form Hexanoyl-ACP.

Hexadecanoyl-ACP is formed as a result of six consecutive cycles [11], [12], [13], [14], [15], [17], at which point the process of biosynthesis of saturated fatty acids ends by hydrolysis of Hexadecanoyl - ACP and release of Palmitic acid as a final product catalyzed by FASN [11], [12], [19], [13], [14], [20], [15], [17].


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