Changes

==What are Phenylalanine and Tyrosine?==

==What are Phenylalanine and Tyrosine?==

Phenylalanine and tyrosine are '''aromatic amino acids each containing a benzene ring side chain'''. Phenylalanine is converted to tyrosine in both dogs and cats and only phenylalanine is considered an essential amino acid. Tyrosine production accounts for half of the total phenylalanine requirement in the diet<ref name ="Milner">Milner JA. Phenylalanine and tyrosine requirement in immature beagle dogs. J Nutr 1984;114:2212-2216.</ref>, and both amino acids are considered together when determining the daily requirement. Phenylalanine is converted directly to tyrosine via phenylalanine hydroxylase in the liver; this is a non-reversible step in phenylalanine degradation. The addition of dietary tyrosine can “spare” phenylalanine reducing the phenylalanine requirement. Phenylalanine and tyrosine are '''neutral amino acids and are both gluconeogenic and ketogenic'''. They are absorbed by a neutral amino acid transporter in the small intestine (particularly the jejunum) and are actively reabsorbed in the proximal tubule of the kidney.

Phenylalanine and tyrosine are '''aromatic amino acids each containing a benzene ring side chain'''. Phenylalanine is converted to tyrosine in both dogs and cats and '''only phenylalanine is considered an essential amino acid'''. Tyrosine production accounts for half of the total phenylalanine requirement in the diet<ref name ="Milner">Milner JA. Phenylalanine and tyrosine requirement in immature beagle dogs. J Nutr 1984;114:2212-2216.</ref>, and both amino acids are considered together when determining the daily requirement. Phenylalanine is converted directly to tyrosine via phenylalanine hydroxylase in the [[Liver - Anatomy & Physiology|liver]]; this is a non-reversible step in phenylalanine degradation. The addition of dietary tyrosine can “spare” phenylalanine reducing the phenylalanine requirement. Phenylalanine and tyrosine are '''neutral amino acids and are both gluconeogenic and ketogenic'''. They are absorbed by a neutral amino acid transporter in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] (particularly the [[Jejunum - Anatomy & Physiology|jejunum]]) and are actively reabsorbed in the [[Nephron Microscopic Anatomy#Proximal Tubule|proximal tubule]] of the kidney.

==Why are they Important?==

==Why are they Important?==

Phenylalanine and tyrosine are '''incorporated into structural protein''' and the presence of the hydrophobic aromatic side-chain will induce a fold in the protein structure. In addition to being required for normal growth, both phenylalanine and tyrosine are further incorporated into key regulatory hormones and compounds.  

Phenylalanine and tyrosine are '''incorporated into structural protein''' and the presence of the hydrophobic aromatic side-chain will induce a fold in the protein structure. In addition to being required for normal growth, both phenylalanine and tyrosine are further incorporated into key regulatory [[Hormones - Anatomy & Physiology|hormones]] and compounds.  

Phosphorylation of tyrosine residues by tyrosine kinase plays a role in cellular replication and signalling and abnormal tyrosine kinase activity has been associated with loss of cellular regulation and development of a number of cancers in dogs<ref>Mariotti ET, et al. Canine pulmonary adenocarcinoma tyrosine kinase receptor expression and phosphorylation. BMC Vet Res 2014:10:19.</ref><ref>Dickerson EB, et al. Matinib and Dasatinib inhibit hemangiosarcoma and implicate PDGFR-β and Src in tumor growth. Trans Onco 2013;6:158-168.</ref>.

Phosphorylation of tyrosine residues by tyrosine kinase plays a role in cellular replication and signalling and abnormal tyrosine kinase activity has been associated with loss of cellular regulation and development of a number of [[Neoplasia - Pathology|cancers]] in dogs<ref>Mariotti ET, et al. Canine pulmonary adenocarcinoma tyrosine kinase receptor expression and phosphorylation. BMC Vet Res 2014:10:19.</ref><ref>Dickerson EB, et al. Matinib and Dasatinib inhibit hemangiosarcoma and implicate PDGFR-β and Src in tumor growth. Trans Onco 2013;6:158-168.</ref>.

==Roles in the Body==

==Roles in the Body==

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition GGP]]

[[Category:To Do - Nutrition preMars]]