[25, 26] Candida spp., especially C. albicans, are able to produce and secrete various hydrolytic enzymes, particularly proteinases, lipases and phospholipases.[21] Shimizu et al. [27] and Abu-Elteen et al. [28] demonstrated the relevance of proteinases, hyaluronidases, condroitinases and phospholipases as virulence–related factors, reporting that secretory strains of Candida spp. showed an increased ability to invade tissues compared to non-secretory strains. According to Costa et al. [29], the activity of

proteinases and phospholipases is directly related to the promotion and establishment of infection. According to studies by Noumi et al. [30], hydrolytic enzymes and adhesins produced by C. albicans present themselves as the largest factor RAD001 research buy associated with virulence, a fact previously suggested by Neugnot et al. [31]. Secreted aspartic proteinase (Sap) was first described in 1965 and was named Candida acid proteinase due to its optimal activity at acidic pH ranges and

because it was primarily found in yeast of the genus Candida.[32, 33] Sap may be considered selleck chemical the most important hydrolytic enzyme among the virulence-associated factors of Candida spp.[34] Saps are believed to contribute to the adhesion and invasion of host tissues through the degradation or distortion of cell surface structures or the destruction of cells and molecules of the immune system, to avoid or resist microbicidal attack.[35, 36] Saps have a broad substrate specificity and are able to degrade a variety of human proteins such as albumin, haemoglobin, keratin, collagen, laminin, fibronectin, mucin and almost all immunoglobulins, including immunoglobulin A, which is resistant to the majority of bacterial proteinases.[37]

Basically, these enzymes are involved in the digestion of proteins by providing nitrogen to aid the survival of fungal cells.[38] At first glance, they appear to be acquiring nutrients; however, Saps may have developed other functions related to virulence such as degrading structural proteins Dynein and proteins of the immune system.[20, 21] In C. albicans, the production of Sap is encoded by a family of 10 SAP genes that are grouped into six subgroups or subfamilies: SAP1-3, SAP4-6, SAP7, SAP8, SAP9 and SAP10.[39-41] Gene transcription generates isoenzymes, named due to conformational and structural similarities among them.[40, 41] Sap1–Sap3 share 67% genetic identity and Sap4–Sap6 share as much as 89% identity. Sap1–Sap3 and Sap4–Sap6 are closely clustered. Sap7 only shares 20–27% identity with the other Sap proteins and is externally positioned. Sap8 is related to the clusters formed by Sap1–Sap3 and Sap4–Sap6. Sap9 and Sap10 differ from the other Sap1–8 isoenzymes and constitute a distinct group (Fig. 1).[42-44] All members of the family of Sap proteins possess four cysteine residues and two conserved aspartate residues.