At sea level, a normal blood oxygen level (saturation) is usually 96 - 97%. Although there are no generally accepted classifications for severity of oxygen desaturation, reductions to not less than 90% usually are considered mild.Dips into the 80 - 89% range can be considered moderate, and those below 80% are severe.t sea level, a normal blood oxygen level (saturation) is usually 96 - 97%. Although there are no generally accepted classifications for severity of oxygen desaturation, reductions to not less than 90% usually are considered mild.
Because all amino acids contain amine and carboxylic acid functional groups, they share amphiprotic properties. Below pH 2.2, the predominant form will have a neutral carboxylic acid group and a positive Î±-ammonium ion (net charge +1), and above pH 9.4, a negative carboxylate and neutral Î±-amino group (net charge â1).
About 9 amino acids have non-polar R-groups and are relatively hydrophobic. Another 6 amino acids have strongly polar R-groups which readily attract water molecules. These are hydrophilic amino acids. The remainder, about 5 amino acids, have R-groups which can ionize. At normal cellular pH's these R-groups become electrically charged, making them even more hydrophilic than the polar amino acids. Any of the 20 different amino acids can occur in any position along a polypeptide chain.